replace steam boiler(and what about A/C) or convert to heat pump?

2 years ago

We have an 1850's 2-story house in the mid-Hudson valley in New York. Heating has always been an oil-fired one pipe radiator steam system. No air conditioning. We recently started looking into A/C and also found that one section of the boiler has corroded, so now we need heat and, if possible, A/C. We have a separate oil-fired hot water heater.

We have had two main proposals:

1) Replace the steam boiler, and add ductless mini-splits all over the first floor for A/C, with an A/C (or possible heat pump) system in the attic for the second floor.

2) Don't use steam any more. Install a cold climate Bosch heat pump in the attic for the second floor, and a second heat pump in the basement with ducts leading to vents cut in the first floor.

I have been doing a lot of reading and see a lot of articles about how heat pumps don't work well in the northeast, but many of these articles are old. Does anyone have recent experience with these newer heat pumps? Not using steam and the radiators is a big leap for us.

We're also not crazy about how the ductless units would look in an old house, and we'd essentially be having two complete heating systems.

Thoughts? Experience with cold climate heat pumps?

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Charles Ross Homes

2 years ago

"In terms of the Bosch I doubt it would make much difference if you sized it for heating... unless you needed more heat than a 5 ton unit can produce."

Name plate capacity of a heat pump refers to cooling mode only. The term "ton" refers to a ton of refrigeration which is 12,000 BTU/hr. Heating capacity is usually referred to in BTU/hr. The heating capacity of a heat pump declines as a function of decreasing temperature, so it can't be labelled without defining the outdoor conditions. Stated otherwise, a 5 ton heat pump does not have the same heating capacity as a 60,000 BTU/hr furnace--the capacity of which is independent of outdoor conditions.

"However, the Bosch can deliver heat down to 5F."

That statement can be a bit misleading. While a particular heat pump may be able to extract useful heat down to 5F, that doesn't guarantee it will be able to do so at a sufficient rate to meet the required heating demand without supplemental (backup) heating e.g., electric resistance heat strips.

When evaluating a heat pump in heating mode, we're interested in determining the balance point--the outdoor temperature at which the heating load of the home and heating capacity of the system are equal. Below that temperature supplemental heating will be required. For most heat pump systems and most homes (excluding uninsulated homes and super-insulated homes) the balance point usually falls in the 30 F to 35 F range. To be clear, that doesn't mean a particular heat pump won't extract useful heat below that temperature---it just means the amount of heat won't be sufficient to meet the total heating load required and backup heat will be needed.

I suggest you consult with an HVAC design professional who can calculate the heating and cooling loads for your particular home and your particular climate zone. Those can be used to select the appropriate equipment and to design the duct work if you elect to go with a ducted system.

And, for what it's worth, mike_home has been a contributor to this forum for a number of years. In general, his posts suggest that he knows what he doesn't know. That's more than I can say for some "professionals" here on houzz.com

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Comments (13)

mike_home
2 years ago
Is natural gas available? If it is then if you do go with option no. 1, then I would recommend a gas fired boiler. The installation cost will be higher, but I think the pay back will not be long. If gas is not available then I think you are better off with option no. 2. I say this even though an 1850's house should have the charm of a one-pipe steam system. I grew up with this type of system and it bring back fond memories.

I assume the Bosch heat pump is the inverter type. It is expensive but they perform well in cold climates. You will have to install a back up heating which are usually electric heat strips. I imagine house built in the 1850's is not well insulated and has a large heating and cooling load. The heat pump needs to be sized for cooling. It could be undersized for heating. The heating strips would make up the difference. Heat pump technology has improved over the years so that it can effective in the North East.

If you post the cost of a gallon of oil and your electric and gas rates, a relative cost comparison can be done.
jed14 thanked mike_home
jed14
Original Author
2 years ago
Thank you, mike.

Natural gas is available, although I understand we would have to convert the water heater also, since they both use the same flue.

The Bosch heat pump that was proposed is the inverter 2.0 series, with the electric heat strips. I'm glad to know they perform well in cold climates! I didn't know it should be sized for cooling - that's a good tip.

I believe these are our current rates:

Electric - 19.6 cents per kwh

Gas - $2.54 per ccf

Gallon of oil - 3.12 (we haven't gotten oil lately, but that's the current NYS average)

If these don't make sense, I may have gotten something wrong.

Thank you!
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The aluminum wiring is indeed another issue, but probably not related much to this because any type of additional heat you'd put in would be on its own circuit with its own wiring. Almost all houses I've seen have aluminum wiring for their service entrance wiring, and it's not a problem. Aluminum wiring is really only a problem on standard household circuits that have receptacles or switches that were not designed for aluminum, because the expansion and contraction of the aluminum wire (which is greater than that of copper) can cause connections to loosen and get hot. But if you've got receptacles rated for aluminum, or both aluminum and copper, you should not have this problem. But back to the heat pump issue, since you have no need for cooling, and you are only using 100 gallons of oil per year, I'm going to say the heat pump probably does not make sense. I think in Canada you use Imperial gallons, but I am used to thinking in U.S. gallons, so let's say you're using 120 of those to adjust for the difference in measure. At current U.S. prices that would be about US$500 in oil. Is that about right? Assuming your boiler is 70 percent efficient, you're using about the same amount of heat you could buy with about 3,500 kilowatt-hours of electric resistance heat (baseboard, fan-forced wall unit, etc.). I think in most parts of Canada your electric rates are pretty reasonable, but even at U.S. 10 cents per kwh, which might be more than what you pay, that's $350 in electricity to duplicate with electric resistance heat what you're paying $500 for with oil, resulting in a $150 savings. Baseboard heaters cost less than $50 apiece, and you have individual room control, which works well in your situation since you have alternative heat sources available and would just use the electric heat to supplement that. Possibly you could increase your savings further with electric heat by heating only the rooms you need (such as your bedroom(s) at night), whereas the boiler was heating the whole house. You might be able to do it without upgrading your service if you do not install an excessively large amount of wattage, which might be possible given your moderate climate, but you'd want to have an electrician evaluate that.
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I feel your pain re conversion. Practicality is paramount most of the time. I understand that in the old days, conversion was not uncommon with two-pipe systems. it might be practical with an older, updated home with all of its original radiation. That is for the same reason that an efficient modulating-condensing boiler can often be installed and run at a lower temp than the original hot-start, bang-bang boiler. If the home's envelope has been significantly improved via insulation and air sealing (better windows and door included), there is radiator way beyond the need so they can run cooler. If I were you, I'd look into it since you have time. I understand that with a steam boiler, you have to size wrt the radiation, you can't right-size the boiler for the heat loss of the house. You end up with an oversized boiler cutting efficiency even more. You may just be able to switch to hydronic. With your cast iron radiators, it could be a beauty of a system compared to the folks with fin-tube aluminum baseboard convectors that don't work as well at lower temps. Be prepared, however, for the steam chauvinists to come down hard on you. There are some wonderful steam chauvinists on the two web sites that I posted. If I were a masochist converting from steam to hydronic, I'd post my plans there :-) I do not believe that there are any reasonably-sized steam boilers that make even close to 90%. A good mod-con water boiler with a well-designed system can make upwards of 98% most of the time. If you have an exceptionally tight house, in a mild climate, that won't make much difference in cost. Steam heads argue that steam does not consume electricity for circulating pumps and draft inducers. How does that add up? Good question. Then there is the fact that your steam pipes will not freeze if the boiler quits on you. It is not just my conclusion that steam workers are hard to find. I've seen and heard it from many quarters. I don't know if you are urban or rural. The latter is really tough. Even in urban areas of the NE there are complaints.
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We've been waiting on the company we found to do the repairs so we're just trying to get by for the time being... they are pretty back logged apparently. I have a follow up question regarding venting. Our second floor tenant was complaining that his radiator was not getting hot so we replaced the vent, which was actually broken and not letting air out. For the first few days there was even heat on the first and second floors but then all of a sudden we stopped getting any heat on the first floor. We figured this was an overventing issue so we closed the 2nd floor vents more and opened the 1st floor vents more. Because the thermostat is on the first floor, the boiler has been running non-stop. We've turned off the thermostat for 2 hours to try and get all the radiators cold and "reset" (not sure if this is what we should be doing, but with my understanding of vacuum in the system, this was required or the 2nd floor radiators would still keep taking all the heat regardless of any venting changes we make) We've done this several times and still no heat on the first floor. Since the change in venting is what caused this issue, what venting change do we need to make to get heat back on the first floor? Are we correct, that the system needs to go cold before we can see if any change we've made to venting works?
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mike_home
2 years ago
The electric rate is high but in line for NY. The fuel oil is what i would expect. The gas rate seems really high. Check that number again.
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Austin Air Companie
2 years ago
last modified: 2 years ago
The Bosch heat pump that was proposed is the inverter 2.0 series, with the electric heat strips.

If you have natural gas available why not put in gas furnace with the Bosch 2.0? You then use a dual fuel kit to make it work right.

Then what you pay less for: electric or gas and you can alternate between the two. Or if it's really cold just use gas heat. However, the Bosch can deliver heat down to 5F.

The bigger question is where are you getting the Bosch from?

Can't get them here until maybe Dec. or January 2022. ----- If you need it, want it, can find it? Don't wait long. (Long meaning a few days to a week.)

Note: Sizing isn't the issue people think it is with the Bosch. They only make 2 sizes. 5 Ton and 3 Ton. So if you think you are going to size it specifically... well home owners and others that like to "try their hand" at a skilled trade?

I know Mike is trying to be helpful... but? (what you don't know isn't going to help anyone here.)

In terms of the Bosch I doubt it would make much difference if you sized it for heating... unless you needed more heat than a 5 ton unit can produce. --- If you sized it for 5 tons of heat and then later found some problems and realize 4 tons is what you need for cooling... well that same model can be "configured" to 4 ton operation.

Same thing with the 3 ton model... it can be "configured" to 2 tons.

Why you can't "really" get into trouble with the Bosch? It's an inverter. Depending on the model you need it has over 50 speeds of mode of operation. It's design is to run and continually adjust. It does this by ramping (up and down) compressor as well as condenser fan speed at a moments notice.

The bigger problem: Undersizing. Because once it's fully ramped up, that's all you get.

Inverters solve the sizing problem quite well. Provided of course the people you use know what they are talking about.

I service the Katy, Texas area.
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Austin Air Companie
2 years ago
Yes of course you can also choose "Builder Grade Information" via Mr. Ross.

(The "let's find something to argue about" builder. Personally I think he just likes to hear himself yack.)

Why do they call it builder grade? You know.
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Charles Ross Homes
2 years ago
@Austin Air Companie

I suspect folks down in Houston know a lot more about air conditioning than they do heating. My guess, after the "big freeze" is that they'll be learning more about heat. Your post makes it evident that you don't know much about heat pumps in heating mode. You might want to well, chill a little on the topic until you've leaned something worth sharing. Or you could continue your well exercised tactics of diverting and redirecting when someone takes issue with your misinformation. And when that tactic doesn't work you can always result to put downs and name calling. This is houzz.com, Ray, professionals shouldn't behave like third graders on the the playground. Grow up.
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Austin Air Companie
2 years ago
last modified: 2 years ago
And when that tactic doesn't work you can always result to put downs and name calling.

Actually that is the reverse... this is what Mr. Ross does....

Mr Ross should take his own advice...("grow up") stop calling people names. (If you can't take the heat stop following me into the attic)

From another illustrious failure of a thread that involves a whole lot of keyboard pounding...

Click to enlarge if necessary...

PS: I am from Chicago area over 20 years ago.
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Charles Ross Homes
2 years ago
Ray, I didn't call you stupid. I used a line from the Blue Collar Comedy tour that's made it's way into common usage --if it wasn't already. It's your comment that was stupid.
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Austin Air Companie
2 years ago
Charles... implied means just as much.

I expect nothing but that from a builder. Because the builder's role is to keep costs down, keep thumbs in the backs of people so the builder makes more $$$. (control those sub-contractors and GC's)

It's your role being played out over and over. Belittle and keep the peasants & peons in line.

You're a builder you can't help it. Maybe you come here for pity?

I've been in HVAC for 27 years, how you act or what you say, how you say it --- I am acutely aware nothing has changed in those 27 years.

Now will this invoke change on your part... or more pity for you?
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Charles Ross Homes
2 years ago
@Austin Air Companie

I don't know what your experience with builders has been, but you apparently paint them all with the same brush. Fortunately, clients don't. There are builders who build tract-type and entry-level multi-family homes and others who build architect-designed high-end custom homes, like our company.

We've built custom homes for engineers, architects, and retired admirals. One reason we get selected is because we understand and incorporate building science principles in our designs. We are involved in the design of the mechanical systems in each of our homes (I'm a licensed professional engineer and I worked in industry on a wide variety of air conditioning and refrigeration projects over 18 years before making the career change to custom home builder.) We don't put cheap anything in our homes because our clients don't hesitate to call us if there are problems with their homes even 20 years after completion.

Houzz.com is a forum which enables houzzers to collect information from a variety of posters. When there's misinformation spread, you can bet I'll continue to challenge it. Houzzers can decide for themselves what information to keep and what to throw away.
jed14
Original Author
2 years ago
Gentlemen, Thank you all for your comments, but this thread has gone a little astray from my original question. We have engaged an HVAC professional who has done a Manual J calculation, knows our climate, and has lots of 5 star reviews. We will probably go with the heat pumps, and your comments validating that these are decent units have helped. NY state, in conjunction with local utility companies and certified clean heat contractors, is offering sizeable rebates, which is also a factor. Thank you all!
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Austin Air Companie
2 years ago
Gentlemen, Thank you all for your comments, but this thread has gone a little astray from my original question. We have engaged an HVAC professional who has done a Manual J calculation, knows our climate, and has lots of 5 star reviews.

Yeah it's a rather unfortunate attribute of conducting business here... politics of this board get in the way.

I'm at least glad that you were able to read between the lines to determine your path forward.

The Bosch inverter (if you can get one) is a remarkable machine for what it does. When done properly IMO there is nothing that comes close to this beast. I know I love mine.

I service the Katy, Texas area.

replace steam boiler(and what about A/C) or convert to heat pump?

Charles Ross Homes

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replace steam boiler(and what about A/C) or convert to heat pump?

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