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Furnace running below rated Heat Rise

Keith Hoar
2 years ago
last modified: 2 years ago

I found the manual for my HVAC unit (installed 2011) and calculated the heat rise to be 19-20 degrees (assuming 220V and 1600 CFM [a mid-point on the unit's CFM table]).

Formula: TR = (kW X 3412) X Volt. Corr. / (1.08 X CFM); TR = (10 X 3412) X .92 / ( 1.08 X 1600) = 18.17

With a cold air return temp of 68 and a heat rise of 19-20, flow from a heat register should be 87-88. The measured temp at a heat register is consistently 79-80 max (over 2 days). So, in my situation the heat rise is only 11-12 degrees. Given that, my furnace is running at 58-60% of its rated output. Does this seem reasonable?

I have attached a photo of the air handler in the attic. Heat strip is at beginning of the transition piece.


The transition from air handle to main trunk was rebuilt due to large gaps and leaks.

Comments (44)

  • Keith Hoar
    Original Author
    2 years ago

    No sir. The highest blower speed available for my air handler is 2100 CFM. If I substitute that into the formula it calculates to 14-15. Can't be certain, but I very much doubt if it is set to the max speed.

  • PRO
    Austin Air Companie
    2 years ago

    There is no "set heat rise" for an electric furnace as the strip heat is sold in "kits".


    The amount of heat you get is depending upon how many strips you have. However when it comes to electric heat, the more electric strips you have the costlier it will be to run the electric furnace.


    That being said, the heat strips draw alot of power so the electrical circuits to this AH have to be capable of servicing a larger heat kit set up. (many times there's more to it than just adding heat strips as you will need the electrical over head to pull it off) This may be part of the trouble as many times in the south, heating isn't as important to some people. So they cut some corners to reduce costs when the system was installed.


    I had a customer with electric heat years ago call me and was saying hey I think I have a problem with my heat. I go out there spend 30 mins testing the system and within that time all the heat strips she had fully engaged. The thing was spitting out the heat like crazy.


    She said what did you do? Turned on the heat, let it run. She looked at me with this blank look on her face and said: Oh, I can't do that my electric bill would be too expensive.


    I told her: Ok, if that's the case what you need is a heat pump. Luckily for you, you also need a new AC, so we can knock out both things at once. She did that and the issue was resolved.


    I service the Katy, Texas area.

    Keith Hoar thanked Austin Air Companie
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  • Jake The Wonderdog
    2 years ago

    So let's look at this from a system view:


    Your formula uses kw - is that based on the nameplate or is that based on actual measured amps x measured volts?


    To answer your question you need to measure the actual current the thing is drawing, that will tell you if all of the electrical strips are working. If the current is below expectations, then track down open coils, open high limits, etc. If there's an open high limit, find out why (air restriction, for example).


    If the current is what you would expect for the kw rating, then I would suspect air leakage from the attic on the return side. The idea being that your actual return air temp is really lower than what you think it is. You can confirm this by drilling a small hole in the return plenum near the furnace and insert your temp probe there. You can tape the hole when you are done.


    Keith Hoar thanked Jake The Wonderdog
  • Keith Hoar
    Original Author
    2 years ago

    Thanks again sir for another GREAT answer.

    I calc'd the heat rise using the formula and tables in the manual. According to the manual, the model # determines the kW rating.

    The furnace has only one heat strip. I watched and questioned the tech when he removed the old mal-fitting transition. The heat strip is right at the very end of the air handler where the transition attaches. At some point a previous owner turned the double garage into a living space. At the end of the old main trunk they added a 12" Insulated Flex Duct that goes to 2 registers in the old garage ceiling. There still seems to be adequate air flow from most registers.

    Using R-13 fiberglass batting, we wrapped all the main output trunk. We could not do the sub-branch (15"X12" metal) that feeds the lower floor bedrooms as it runs between the rafters and vertical braces so tightly you couldn't slip a piece of paper between them. Thankfully, I have measured a 3-4 degree rise in temp at one bedroom register. My heat rise calc is after the addition of the insulation. It is forecast to get down to 24 degrees Saturday morning. I will be interested to see what the register output temp is then.

    I hung the remote sensor for my weather station in the crawl space. So far, the low has been 55 and the high 61 with the outdoor temp from 35-72. The water lines are old, uninsulated, 1/2" pipe. I want to make sure Saturday's doesn't cause any freezing.

    We have been in the house only 7 months and due to a "sudden" development we "may" be forced to move again. So, until we know for certain, I want to do whatever I can to reduce the high electric bill. I suspect we have done about all we can without spending a boatload of money.

  • Keith Hoar
    Original Author
    2 years ago
    last modified: 2 years ago

    Reply to "Jake The Wonderdog": I had a H&A company out to check the furnace. He measured the current and said it looked okay. They rebuilt the old transition piece. It had gaps as large as 2 inches. Also, look at my reply above. The cold air return is now sealed and insulated.

  • Jake The Wonderdog
    2 years ago

    @Keith Hoar

    I realize you may have to move again - I'm sorry. I get it that you are trying to troubleshoot the high energy bills and don't want to get this far into the weeds - or drop a ton of money.

    Here's the bigger picture: Your home was built without much insulation and with HVAC that was cheap to install, but expensive to operate. I see that a lot in older homes. Climate change is making all of those decisions worse. To make the home economical will require insulation first, and energy saving appliances as it comes time to replace them. None of that is cheap.


    Below is written for the technical troubleshooters:


    So... math is math. If you really aren't getting the heat rise you expect, then either the formula is wrong, or the inputs are wrong.


    I didn't check the formula that you used, but assuming it's correct, then one of your inputs isn't correct.


    You can do this sort of check based on assumptions (the fan speed, the kw rating on the nameplate) but if it's not right, you have to actually measure these things. The most common issue I've seen are heat elements not working (for various reasons). You might have to actually measure CFM.



  • Keith Hoar
    Original Author
    2 years ago

    You said, "...far into the weeds". That's just me. I am a database designer/business intelligence expert by trade. I lived in the weeds designing data warehouses. I worked on a $143 Million system migration. I wasn't satisfied until everything balanced to the exact penny!

    Here is the formula listed in the manual: TR = (kW X 3412) X Voltage Corr. / (1.08 X CFM)

    I had measured across one phase while wiring the new garage we built and it was 110-112V. So, I picked 220V for my calculation. I don't have anything to measure the air flow so, I used 1600 CFM, a mid point in the fan speed setting table shown in the manual.

    That made my formula: TR = (10 X 3412) X .92 / ( 1.08 X 1600); TR = 18.17. I felt that was close enough for my "sanity check" type comparison.

    My utility provides download of daily usage statistics. (I will be uploading it for analysis in re: to kW usage per HDD or CDD. I'm hoping I will see some change at the point where we added insulation.) My bill for January as of 1/18 was already $210 (1598kW X .1316/kW) and there are 13 days to go and the next 5 days are to be much colder. OUCH!

    BTW - we also have added 30 bales of cellulose insulation to everything but the converted garage.

    I'd love to have the H&A guy come and measure/check/suggest/etc. However, they charge $90 just to roll into the driveway and then $120/hr. When they were here to replace the transition, the tech guessed $6-7K to replace to the old trunk lines. We didn't discuss replacing the air handler/furnace with a new "gas" furnace or heat pump.

    I think I have done everything I can without dropping a ton of money. Jake, I really appreciate your time to answer. If I find anything interesting in my analysis, I will report it here.

  • PRO
    Austin Air Companie
    2 years ago

    I think I have done everything I can without dropping a ton of money.


    You could buy a few space heaters, taking care that you don't make matters worse and burn your house down. It doesn't get any cheaper than that... but it's a trade off and you'll see why pretty quick. (control, noise, hot / cold spots --- too hot, too cold turn up, turn down etc.) But in a pinch there is no better cost effective solution than that when it comes to electric only heat.


    You can minimize the operational cost by choosing which rooms get the heat. Set your regular HVAC T-stat around 55-60 so pipes are less likely to freeze.



  • Keith Hoar
    Original Author
    2 years ago

    I hope I'm not chasing ghosts.

    I hung my old thermostat from my bedroom register to check the air flow temp. After noticing a 5 degree difference from afternoon to morning (outside temp varied from 50 to a low of 21 degrees), I hung the same thermostat from several registers. The temp readings on the attached drawing were all taken during a 20 minute period when the temp was 47 degrees.

    The proportions on the drawing may not be accurate as I roughed it out in 20 minutes using Excel.

    What baffles me is the kitchen reading that is three degrees lower than bedroom 1 which is much farther from the heat source. The distance from the air handler to the bend is approx. 20 feet. The cold air return and heat run to the bend are wrapped with R13 batt insulation.

    Any ideas why there would be such a temp difference?

  • PRO
    Austin Air Companie
    2 years ago

    Cold air return is going to do what?


    Pull air? where is this air coming from? What temperature is this air that is moving past Kitchen register to get to cold air return? The duct layout? what path is forced air going to take? the path of least resistance.


    All of this is considered design. Unfortnately crunching numbers in a spreadsheet is not going to resolve this. When design is poor? I rip it all out / start over with a better design. The design would include duct system, equipment choices, equipment layout etc.


    No you're not chasing a ghost. A ghost is invisible. This is not invisible, the problems (which are many) are all too telling to me.


    I service the Katy, Texas area.

  • Keith Hoar
    Original Author
    2 years ago

    The pull (cold) air return has three sources: one 12"X12" at floor level from each upstairs bedroom and one 24"X24" at floor level directly below cold air return in drawing above.

    The thermostat was suspended by a wire 1 inch below each ceiling register.

    I agree with the "poor design" statement. Given a big old pot of money, I would build an enclosure in the corner where the screened porch meets the house (large enough for a propane water heater and furnace). That is where the new propane line enters the crawl space. Then I would put the ducting in the crawl space and install floor registers where they should have been in the first place.

    However, being on a fixed income and with prices spiraling out of control, that likely won't happen. I may have a sit-down with the H&A company and see what suggestions they can make.

    We live near Hattiesburg, MS. We expected utility costs here to be lower as it NOT SO STINKING COLD!

    Thanks again for another great answer.

  • PRO
    Austin Air Companie
    2 years ago

    I understand the dilema of not enough money. I hear it all the time, many times these situations were born out of not having enough money prior when the original system was installed.


    It's the one nut, that many that view this occupation take for granted. I am not one of them.


    That said, it's only money and proper design that is going to truly fix this.


    The next best option is space heaters. Just use common sense when using them, no extension cords / over loaded outlets etc. Don't place on something it can tip over, unplug when leaving room things of that nature.


    If it were me, I would not choose propane... because propane is not cheap either. I would start setting money towards this project. (if you plan to stay here) I would choose a heat pump with back up electric strip, even if you can't afford the inverter with everything else you need to do duct work wise.


    Realistically the duct work needs to do away with turns in direction of air flow. You've got conflicting pictures I am not sure why the text type picture has a circular bend going the opposing way?


    The regular picture you show of your equipment looks straight? with what looks to be an attic wall to the left of the picture? Not sure.


    Is there an interior atrium in this house? They did some funky builds in the late 70's early 80's here, if this is your era of home build? I'm not sure.


    If you're planning to move again soon, I would just sell it as is I doubt you would recoup the investment.





    Keith Hoar thanked Austin Air Companie
  • Keith Hoar
    Original Author
    2 years ago

    House was built in 1965. No big atrium. In the photo, you can see the monstrous cold air return "box" at the very end, wrapped in batt insulation. The two round, upward air return ducts go to the upstairs bedrooms ceilings and down stud cavities.

    The drawing is accurate. Ten feet behind where I was standing the duct becomes smaller and makes a 180 degree bend and runs along the left side of the air handler butted up against the rafters.

    I have observed that when the outside temp is in the 30s, the register air temp is 78-79. When the temp is 50 the register air temp is 83-84. It would seem cold attic air is still infiltrating from somewhere.

    The move/not move "unknown" should become clear in a couple of months. So, for the time being we will just "suck it up" and divert funds from somewhere else to cover the electric bill. During this cold snap, the daily stats from the electric utility shows a cost of $17-$18 per day. It is supposed to warm up a little for a few days and then back to to the mid twenties.

    Thanks again.

  • PRO
    Austin Air Companie
    2 years ago

    The two round, upward air return ducts go to the upstairs bedrooms ceilings and down stud cavities.


    The drawing is accurate. Ten feet behind where I was standing the duct becomes smaller and makes a 180 degree bend and runs along the left side of the air handler butted up against the rafters.


    Ok I didn't realize this was 2 story house. Because heat rises the upstairs will be warmer 9 times out of 10. So this is one more reason why the difference in temps from one area to another. It's not significant. I've seen differences from one side of house to another upwards of 10F degree difference. I seen just as much or more difference from upstairs to downstairs as well.


    So given the diagram has more clarification I think it was installed the way it was due to no room at the inn for proper HVAC. Really the HVAC equipment should be flipped the other way rather than having duct work that does a 180 degree turn. This just adds to problems when things are done this way.


    However this "flipping" has challenges due to no room. Because if you flip it the access to equipment servicing is then blocked by it being up against the roof line. In this fashion is why things get blamed on the builder. Not having service access to equipment would be against code. Manufacturer guidelines require at least 24 inches for service access.


    The builder hires a HVAC contractor and they are supposed to make it work. So because there is no room this it what you get most of the time in my experience.


    With that all being said the difference when it's warmer outside from when it's colder is capacity related. There is a heavier load on the equipment when it's colder. While insulation can help this, it is not the only thing to consider in terms of capacity or the amount of heat a system is capable of delivering under certain load conditions.

    Keith Hoar thanked Austin Air Companie
  • PRO
    Charles Ross Homes
    2 years ago

    "With that all being said the difference when it's warmer outside from when it's colder is capacity related."


    What?


    The amount of heat produced by electric resistance strip heaters--which the OP's system has (or even a gas furnace for that matter)-- is not a function of the outdoor temperature. For resistance heaters, a kW of electrical energy input = a kW of thermal energy output. The heating capacity of a strip heater is stated on the nameplate at a particular voltage. It's a constant.


    What varies as a function of outdoor temperature is the heating load--not the capacity of the heater. It's an important distinction and one that no competent HVAC designer would confuse.

  • PRO
    Austin Air Companie
    2 years ago

    What varies as a function of outdoor temperature is the heating load--not the capacity of the heater.


    True. But if the heater is undersized for the load being placed upon it?


    This is why heating loads are calculated Charles. When it comes to air handlers / fan coils -- the heating component is varied because the installer picks and chooses how many or how few electric heat strips are used at the time the system is installed.


    I can get electric strip heat kits in a wide variety of sizes. The bigger the heat kit, the more it costs the more heat it will produce if larger kit. If you don't have the electrical infrastructure to run the kit chosen? If you're complaining of high electric bills?


    The bigger more capable the heat kit is, the more heat it will produce.


    If the fire isn't hot enough put another log on the fire, Charles.



  • PRO
    Charles Ross Homes
    2 years ago

    Every trade has its trade-specific terminology. A competent HVAC designer knows the difference between the capacity of a heater and the heating load it needs to be designed to meet. They don't mix up their terms. That's one way to tell a pro from a poser.

  • Keith Hoar
    Original Author
    2 years ago

    I still believe I have leaks in the ducting system.

    Here's what I noticed last night: The new thermostat switches from 68 to 66 at 10:00 p.m. At 10:40 furnace had not run since before 10:00. The old thermostat hanging 1 inch below ceiling register indicated 60 degrees while the room temp was 66. That would make me think cold air is leaking down from the attic.

    If I could just get my books on Amazon to sell, I could afford the upcoming, ridiculous electric bill.


  • PRO
    Austin Air Companie
    2 years ago

    I have observed that when the outside temp is in the 30s, the register air temp is 78-79. When the temp is 50 the register air temp is 83-84.


    I know it's most likely a capacity problem or a bank of strip heat that isn't functioning ( bad sequencer etc) Typically I want to see at least a 40F temp rise from room temp.


    So if room temp is 70F I want to see at least 110F - even better if after a few minutes that rise goes to 120F. If the air handler in question doesn't move the temp to cycle off, it is undersized for the structure given the current ambient conditions. Runs and runs, never cycles off. If all you get is 80-85F out the vent it's not likely to be sufficient heat production under all ambient conditions. If it's 60F outside maybe no problem? why maybe? some people don't view comfort the same way.


    Electric strip resistance heat isn't like gas furnace -- this type of heat is "banked" and sequenced to come on in intervals, not all at once. Certainly you can force it to do that by jumpering the banks, but?


    The builder is good at "pretending" he knows what he's talking about. It's more about spinning you in circles talking to him. When I say things I am doing so to help the most peope understand it. I am not here trying to help an engineer understand it.


    My market is primarily made up of regular folk. If you don't understand how I describe it, you aren't going to. Maybe that is the mission of some? You choose.

    Keith Hoar thanked Austin Air Companie
  • PRO
    Charles Ross Homes
    2 years ago

    "If it's 60F outside maybe no problem? why maybe? some people don't view comfort the same way."


    If it's 60 F outside, heat is provided in normal heat pump mode. At 30 F the system is operating in emergency heat mode and the strip heaters should be operating. The OP either has a system with inadequate strip heater capacity or there's a maintenance/repair issue with the existing strips.


    You can infer the same from the OP's original post:


    "I have observed that when the outside temp is in the 30s, the register air temp is 78-79. When the temp is 50 the register air temp is 83-84."


    At least you didn't launch into your Bosch inverter commercial...

  • PRO
    Austin Air Companie
    2 years ago
    last modified: 2 years ago

    If it's 60 F outside, heat is provided in normal heat pump mode.

    Sure if this house had a heat pump. Clearly you didn't read the thread Charles. Just because a house has an electric air handler / fan coil, doesn't mean that people spent extra money for a heat pump. (heat pump was recommended as a way to fix it, that's not what the OP has now.)

    Why? in the south our winters are very short. So spending money on something you might use a couple of weeks of the year are often put on the back burner.


    At least you didn't launch into your Bosch inverter commercial... You didn't read the thread Charles. Due to money, length of time they plan to own the home etc. Bosch Inverter isn't for everyone.


    The OP has made it abundantly clear, he doesn't have the means to spend a boat load of money. Read it Charles.

  • PRO
    Charles Ross Homes
    2 years ago

    There's nothing in the OP's original post that says they don't have a heat pump, Ray. Only information about their electric resistance strip heaters.

  • PRO
    Austin Air Companie
    2 years ago

    This isn't the only thread he's started Charles. I'm HVAC you're a builder. This is just one more reason why you should be you Charles, "stick" to building.


    https://www.houzz.com/discussions/6218713/furnace-running-too-much

  • Keith Hoar
    Original Author
    2 years ago

    Reply to Austin Air Companie: When we had the transition section rebuilt, the H&A tech measured the current pulled by the heat strip(s) and said it looked okay. He also said the 10 KW heat strip(s) was(were) max for that unit. I found the manual and verified that based on the model number.

    I have monitored the register output temp for several weeks. It takes 2-3 minutes for the temp to reach max. The max temp varies from 78-83 depending on the outdoor temp. It reaches the max temp and never varies until the unit switches off. I have never seen any sequencing.

    One day when the low was 30 and the high was 40, the furnace ran for 17.5 hours out of 24. Power consumption for that day was 189KW. Our base consumption (no heating or cooling) is 10-12 KW.


  • Elmer J Fudd
    2 years ago
    last modified: 2 years ago

    If your heating is electrical resistance, the only "fix" is to replace it with either a heat pump or some kind of petro-fuel furnace - either propane or oil.

    Resistance heating is THE most expensive way to go, there is no magic solution to make it more efficient and less expensive to have, other than to keep it turned off

  • Keith Hoar
    Original Author
    2 years ago

    The H&A tech said the air handler and heat strips were installed in 2011 according the model/SN plate. We got "0" information when we bought the house. We believe the house was "flipped" sometime in the past. If that's true. that could account for the less than acceptable installation.

    As I mentioned earlier, we added 32 bales of cellulose insulation to the attic. So far, I cannot see any improvement in the standard analysis methods.

  • Elmer J Fudd
    2 years ago
    last modified: 2 years ago

    "I cannot see any improvement..."

    Unfortunately, it is what it is.

    We boosted the attic insulation in our mild climate West Coast location some years ago and have found the greatest comfort effect is in the summer not winter. I believe that's because in the summertime, there's a greater temperature difference between the attic and the inside of the house than there is in the winter and so the insulation plays a greater role.

    Where you are, if it's 45 degrees outside and you want the inside to be 68, assume your attic is 45 degrees so that's a 23-degree difference. If the sun is shining on that 45-degree day, your attic will be warmer than 45 and the temp difference between it and the indoors will be less.

    In the summertime, when you want the inside to be 75, your attic could be 115 degrees or more. That's a 40 degree or more difference and so having more insulation will make a bigger difference.

    Good luck.

  • PRO
    Austin Air Companie
    2 years ago

    H&A tech measured the current pulled by the heat strip(s) and said it looked okay. He also said the 10 KW heat strip(s) was(were) max for that unit. I found the manual and verified that based on the model number.

    I have monitored the register output temp for several weeks. It takes 2-3 minutes for the temp to reach max. The max temp varies from 78-83 depending on the outdoor temp. It reaches the max temp and never varies until the unit switches off. I have never seen any sequencing.


    Yeah, that heat kit may have been standard issue for your model... but every AH / Fan coil I have ever bought to install did not include a heat kit. This was chosen the time the job was going in. The heat kit comes in a box separate from the AH/ fan coil.


    Today's tech is pressured to sell, that doesn't include upsizing heat kits for old AH or fan coils. The tech would make little money off that, the company he works for? They are in it to win it.

    Sell. They will talk as smooth as butter, most of them. Just as much many on here.


    Why do you think I am the only one here on this board that does what I do? (I am not referring to the builder, or home owners with too much time on their hands like Mr. Fudd. I know all these characters on this board, not personally but through many, many prior 'discussions & threads' on this board.) Keith, you're new here... because you've opened up is the only reason this discussion has gone to the lengths it has gone. This isn't about the other characters on this board. It's only about you... try to not to pay attention to side show antics. ;-)


    Resistance heat strips the more you have (the more you need for capacity) the more electrical overhead you will need. How many individual 240v circuits go to your air handler or fan coil?


    At my house I have (2) 240v circuits. Enough to support in the realm of 20KW that's typically 4 strips but there's a myriad number of ways to get to that tally. The most common strip is 5KW. The more individual strips you have, the more likely they will be 'sequenced' to come on after so much time has passed.


    If all the heat you ever get out your supply vents is in the mid 80F's supply temp--- it's not enough. Those supply temps need to hit at least 115F to 120F within a few minutes of coming on. Gas furnaces on the low end should see 30-35F heat rise, but can have heat rise of up to 60F with gas furnace (depending on MFG) and still be within spec of the furnace. They often list a range. The only reason I mention gas is because that is what you are accustomed to from your previous house in KS.


    The kits come in a wide array... each mfg different as well as different from one model of AH or fan coil to another. I give you some examples...








  • PRO
    Charles Ross Homes
    2 years ago

    "Today's tech is pressured to sell, that doesn't include upsizing heat kits for old AH or fan coils."


    Most HVAC repair/replacement work doesn't require permits (CA being a noted exception) so there is no independent oversight of the work, and no assurance it complies with code requirements.


    The work performed on the OP's home is obviously inadequate for their heating load and climate zone. What we don't know is whether a previous homeowner made an informed choice or not. If it was a house flip, that owner likely chose to do something at minimal cost and hope it would go unnoticed at the time of sale. If it was a resident owner, they probably were the victim of yet another HVAC replacement contractor who didn't know how to calculate a heating load.

  • PRO
    Austin Air Companie
    2 years ago

    If it was a resident owner, they probably were the victim of yet another HVAC replacement contractor who didn't know how to calculate a heating load.


    This house was probably the victim of another builder with builder grade... much of the problems older homes have is a direct result of the builder Charles.


    Look at how tight that attic is / air flow going the wrong way having to do a 180 degree turn? Who is responsible for that? Not the HVAC contractor I can tell you that much.


    Let's just blame the HVAC contractor. Your typical talking in circles. ;-)

  • PRO
    Charles Ross Homes
    2 years ago

    Ray,

    The home dates from 1965. We don't know what if anything is original or what may have been replaced. The only thing we know is that the current heating system is inadequate. Directing the blame without knowing where to direct it may feel good to you, but it does nothing to help the OP or your standing as a "pro."

  • PRO
    Austin Air Companie
    2 years ago

    ha, ha, ha. Charles maybe start a comedy tour.


    Directing blame. Ironically you went there first. Skip your 1 a day +iron today Charles.

  • Keith Hoar
    Original Author
    2 years ago

    We're in the county so there are no building codes. The only pieces that are not original are the air handler and the outside AC unit.

  • PRO
    Charles Ross Homes
    2 years ago

    "Directing blame. Ironically you went there first."


    Actually, Ray--and probably unintentionally--you were the first to assign blame. You opined that "Today's tech is pressured to sell, that doesn't include upsizing heat kits for old AH or fan coils." That implies the HVAC person is to blame because they simply replaced a component without verifying it was adequate for the purpose--and it clearly isn't. I merely pointed out that there are no permits typically required for replacements and no third party quality control so that can be a common occurrence.

  • PRO
    Austin Air Companie
    2 years ago

    Contrary to popular myth, I didn't wake up one day and say "Hey, Today! I'm going to be a Licensed HVAC contractor."


    You think this didn't exist before when I worked as a HVAC Tech? It was bad then, it's worse now... because I actually do this for a living and talk to people? I view that as fact. Charles you would never understand that because: That's not what you do. Irony2. Skip another 1 a day +iron.


    Last year I had a customer who was referred to me by another long time customer up the street from her. I had been out there a few years prior and did a gas 'n' go because she didn't have the money to do anything more than that.


    A few years passed. She was referred again to me by same person as before. I keep records so I know I had been there before. We got to talking only to find out she had called a major company here that will tell you "everything you want to hear" give you free estimates and so on the whole ball of gimmick wax.


    She told me they told her that her system was obsolete and that she needed to replace everything for the tune of $15 grand. This company runs TV commercials non stop here. Take a guess if you're from my area.


    She still didn't have the money to fix her problem (leaking Evap coil) the system used R410a refrigerant. Roughly 8-9 year old system, out of any warranty coverage as the house was a recent build (8 year prior)


    I told her she didn't need everything at this time, the system wasn't old enough. I said there is some risk there the longer you keep recharging this machine without fixing the problem. We continued to recharge it for a couple of years beyond that. 1 re-charge per year, until this past year 2021 it wouldn't hold the charge beyond about 3 weeks.


    At that point she did without until she could afford the repairs. I replaced that Evaporator coil in Early August 2021. Problem solved. System still running... you think after all that she would call anyone but me?


    Check Mate.

  • PRO
    Austin Air Companie
    2 years ago

    We're in the county so there are no building codes. The only pieces that are not original are the air handler and the outside AC unit.


    Yeah this is more common than you would think Keith. There's codes, but to follow those in areas like this is cost prohibitive more often than not, especially with an older build like you have here.


    So because of that, the design of your system isn't changed which is primarily where the problems are. I can tell from the picture there is only (1) 240v circuit going to the air handler, if the strip is 10 KW as you said it's going to pull in the realm of 40 amps, just the strips alone. So just adding a bigger heat kit isn't going to work.


    The HVAC company any of them 9 times out of 10, isn't going to get involved in that unless they have a licensed electrician where they could make the money running new circuit and likely up dating the electric panel to boot. Often times the case in these older builds is there's no extra room in the electric panel for another 240v circuit. If that's the case you're looking at possible thousands more to do update the electric panel. Why the heat pump would make financial sense if this is the case. The heat pump would use the existing circuit already in place, and is more efficient (pay back wise, via use).


    This is why if someone called me with a similar problem like this in my area, I would tell them the path forward is the heat pump at least, because it will pay you back with use, even if you just choose a run of the mill heat pump. An inverter would be better, but well you know. ;-)


    If you open the electric panel and see room for another 240v circuit you could call an electrician pay them to run a new circuit to the air handler to handle another 10kw heat strip total 20 kw. You already know that running electric strip heat is expensive. So doing this has it's consequences.


    You will have to buy a new heat kit, just trying to add an additional 10KW to an existing heat kit, is not worth it in terms of fire risk and so on. The strips can't be touching anything.


    I would never recommend someone attempt this as DIY. If you want DIY, buy a space heater and follow all safety recommendations of those types of appliances. (not saying this is you Keith, but anyone else besides the builder who may read this in the future.)



    I service the Katy, Texas area.

  • PRO
    Charles Ross Homes
    2 years ago
    last modified: 2 years ago

    "We're in the county so there are no building codes."

    Most states adopt a statewide building code. Mississippi was late to the party, but they've had a statewide building code in place since 2014. Counties are required under the law to enforce the code. Folks in rural areas deserve protection from charlatans as much as folks in urban and suburban areas.


    "There's codes, but to follow those in areas like this is cost prohibitive more often than not,"


    When tradesman start deciding which codes to follow and which to ignore they substitute their limited expertise for that of a group of credentialed professionals who have carefully considered code requirements. Codes are developed and revised following a disciplined process with a wide range of stakeholder input. That's the time for trades to weigh in. The alternative is to leave it to the individual framer to decide what's structurally adequate, the electrician to decide whether smoke detectors need to installed and the HVAC tech to decide how to vent a combustion appliance because he knows better. I'm not aware of any codes that would dictate a complete replacement of a component or system, but rather, they require that portions touched meet current code requirements. If a contractor is willing to perform work without a permit, without required inspections and which doesn't meet code requirements, look for another.

  • PRO
    Austin Air Companie
    2 years ago
    last modified: 2 years ago

    When tradesman start deciding which codes to follow and which to ignore they substitute their limited expertise for that of a group of credentialed professionals who have carefully considered code requirements.

    It's decided based on money, nothing else Charles. It's primarily why the house is as it is. You're not going to rob Peter to pay Paul in this situation and be successful.

    If someone has the the budget of $50k to build a house what you gonna tell him Charles? But you'd rather not think about that side of the coin?

    So what makes it different if someone has the budget of $1000 or less to fix their HVAC? Sometimes it's feasible, sometimes it's not... regardless of building code problems.

    Who decides when it comes to how much money? There's always this mentality that you think you can force anything you want on people... even though it's their decision to make - not yours.

    That said, this isn't an excuse to not follow building codes... so don't put words in my mouth that aren't there.


    If a contractor is willing to perform work without a permit, without required inspections and which doesn't meet code requirements, look for another.


    Certain areas do not permit HVAC mods or replacements in existing structures. When you're located in the county (outside city limits) -- the city isn't going to go out there. They don't have the man power to do it.


    This is why -- it's ultimately the home owners choice. They need to do their home work to understand exactly what it is they are buying and what is included in that choice.


    When it comes to new construction, that's a different animal. That most of the time will require permits. This is yet another reason why the builder should do what he does and stop talking about things he has limited knowledge on.

  • PRO
    Charles Ross Homes
    2 years ago

    Ray,

    The OP seems uniformed or misinformed regarding the fact that there is a building code in MS and it applies statewide. It's important they know that codes govern the work, not the whim of some tradesperson. Codes are written to protect people. Trade work should follow them. Period.

  • PRO
    Austin Air Companie
    2 years ago

    Codes are written to protect people. Trade work should follow them. Period.


    True, but these words aren't going to pay for them Charles. Are you going to pay for them?

  • Keith Hoar
    Original Author
    2 years ago

    I am neither uniformed or misinformed regarding building codes.I spoke with the top selling real estate agent in the county and 3 building contractors. They all said the same - No codes out in the county.

  • mike_home
    2 years ago

    I think the more accurate way to state it is: No code enforcement in the county.

  • PRO
    Charles Ross Homes
    2 years ago
    last modified: 2 years ago

    @mike_home,

    I stand corrected: although Mississippi adopted a statewide building code in 2014, there was a provision for counties to opt out if they did so within a particular time window. Some counties in MS did that. In those counties, it's the builder's version of the wild west. No permits. No inspections. No problems; unless you're a homeowner, that is.