Shouldn't that room have external ventilation?

Thank you Mike, for your response.

This happens in the Spring/Summer, though it seems to be happening a lot more this year.

Water temp is 131 (maybe a little high), boiler is 160 on the Buderus. There is some kind of mix valve going into the water tank to keep the temp at a better temp (this was set up by one of the hvac companies). There is also radiant heating. I have measured the temp at the faucet (turkey therm in a large glass of the hot water off the faucet, it is 115) as I have read it should be max 120.

We keep the house temp at 72-74 during the summer, depending on outside humidity. I try to keep basement at 70 to 72 (separate heat/cool zone from rest of house).

Possibly related to this, is that I get a Buderus Domestic Hot Water Heater error that I can clear by bleeding the water out of the pipe connecting to the water tank

For context, I have had five (yes five) different HVAC companies come in to fix the DHW error, all of which say the previous people did not know what they are doing, but none has fixed the problem. They also say that the temp in the room (86) is "normal".

I suppose I can turn back the water temp to 125, but I am not sure how much this will help. I can also keep the temp in the basement higher, but am concerned about humidity down there.

Really wish I had a local company I feel comfortable with

Andy

mtvhike: I believe so, there is some kind of vent/blower (a tall grey cylinder almost a foot wide that exits the top of the room, with a bell bottom bulge near the floor with a fan that kicks off when the heating elements ignite.

You should look into installing a outdoor reset for the boiler. This will monitor the outside temperature and on mild days lower the boiler temperature. This would reduce the boiler temperature from 160 down to the 120-125 range which should be sufficient for heating during the spring and fall. On very cold days the boiler would operate at higher temperatures.

A lower boiler temperature will save energy costs and not heat up the basement. The claim is there is a 1% energy savings for every 4 degrees F. So you you get a 10% savings when operating at 120 degrees.

Where are you located? Hopefully you will find a competent company near you that knows how to service a boiler.

Hi mike_home,

Thank you for the feedback. The Buderus supposedly has all of this - there is an outside temp monitor and a seasonal setting and has ways to optimize its heating based on outside weather.

I do not believe the system is set up properly, but I am having a hard time finding anyone who knows anything more than banging on some pipes and randomly changing settings. I have been through all of the "reputable" places. I tried to contact people who claim to install Buderus systems, but they wont return my phone calls (I am not a builder), and I tried going through Buderus for recommendations.

I have gone through the manuals carefully, and there are instructions for for configuring this based on outside weather, but I am really worried about changing anything on my own.

Who knew HVAC could be so complicated ?

I live in Metrowest Boston

Andy

Andy, Is it a Buderus or a Buderus? An old, hot start boiler or does it cool down completely between space heating cycles and between heating hot water for your indirect tank? I don't know enough about your system to say how you might make improvements. If it is an old boiler, you can't reduce the temperature. How many heat zones do you have in addition to the indirect tank?

I'd start by insulating the hot stuff in the room rather than insulating the room. For starters, make sure all of your domestic hot water pipes are insulated. Insulate the hydronic heat pipes near the boiler if they feel hot or warm.`

Do you have a hot water recirculation system? If so, put a timer on it, or check the existing one so it is not acting like a constant heater. In the summer, when you don't need space heat, you can put a timer on the hot water system so the boiler won't fire to make domestic hot water if you are absent all day for work, school or whatnot. I do hope it is not a hot start boiler, but if it is, you will reduce heating a great deal by stopping unnecessary calls for domestic hot water when you are not there. (Put an override button at the top of the stairs in the event you are home off schedule.)

Get an energy rater in there (BPI or Resnet). MA used to have good energy efficiency programs and maybe they still do. They might pay for the rater and get you discounts or low cost loans to make improvements. The energy rater will help you pick the low hanging fruit for efficiency and lots of that might go to keeping the basement cooler when appropriate. Sometimes energy efficiency mortgages are available that allow you to pay off the cost of improvements at a rate calculated by the energy savings that result from the investment. Replacing an old, inefficient cast iron boiler could reduce waste heat in the basement to pretty insignificant levels. Usually, indirect tanks are well insulated relative to old school stand-alone domestic water heaters, but maybe yours is not so find out. Do you have lots of room in the utilities area? If so, a heat pump water heater for use in the warm times might be a good investment. The energy rater can tell you based on the cost and benefits.

P.S. Surf on over to the Terrylove and heatinghelp.com (The Wall). There are lots of boiler heads on those two boards. Boston should be one of the best areas for boiler experts in the USA. People over there might be able to steer you towards a good company.

Thanks to everyone for their feedback. I want to wrap this thread up, and how I solved this

When I moved in a few years ago, the hot water from the taps seemed very hot, so the HVAC company put in a regulator/mixer.

However, they set the water temp on the Buderus to 140, and mixed it down to 125. I set the Buderus to 130, and set the mixer to keep the water to 125.

Pipes are far less hot, room temp went down from 85 to mid 70's, and everything is a lot better.

Not sure why this became a problem now

Thanks,

Andy

Please be careful. Unless I missed it, we have not been told what model boiler this is, what kind/type or what type of flue. Are you sure it is designed to operate at that low temperature? If not, you could wreck your boiler and your flue/chimney and cause a fire hazard.

Reviewing your description of the problem, since the excess heat thing is new, it could be due to the outdoor reset malfunctioning in effect telling the boiler that it is cold outside.

Thanks for the feedback ionized. I will have this checked out.

It is a Buderus (model G234, with a Logamatic 2107 series controller), and when it fires up, there is some kind of fan system at the bottom of a pipe that runs that looks like the vent to the outside, system is in the basement. What seems to be different now is that the Buderus thinks that is it is summer, which it is, but I did not notice this last summer.

I looked at the install manual and other information at the Bosch web site. I am disappointed in what they offer the residential user and the installer. They give no minimum temperature. They do list the G234x as a non condensing boiler. You could be in for trouble at 130. That is the beginning of condensing conditions in a gas boiler. I'd turn it back up until you can get an answer from a knowledgable source. Even at 140 it could be a problem. You can't have condensing gas in the flue. The condensate will be acidic and can damage some kinds of flues. How is your flue/chimney constructed?

I still recommend insulating the pipes to the indirect tank and the near hydronic heat pipes if they feel warm at all. (Hot pipes get lots of insulation, warm pipes not as much.

One thing that you might do with this boiler is put it on a timer when out of heating season. That way it won't be cycling on and off to keep the hot water tank at a particular temperature when you don't need it. This is not shutting off the boiler and controls, but eliminating the demand for water heating. That will work well if this is a "hot start boiler." If it is a "cold start" boiler, you might consider turning of the boiler entirely in times of no hot water demand. Either way, this will be more useful if you are not at home in the daylight hours and have a large tank. The temperature of the tank might be allowed to drop at night as well. You can probably have an override button placed at the top of the basement stairs if that is convenient.

Some good places for detailed boiler information are heatinghelp.com and terrylove.com. There are lots of boiler heads on both fora.

Hi ionized,

I really appreciate the feedback. I turned the boiler back to 140 and will see how it goes. Looks like the heat wave has broken for now, in any case. I will add some insulation on pipes that get very hot, that is easy and presumably safe to do.

I do not know what kind of flue I have. I will do more checking, problem is, even though I am an engineer, this is not my area, and a little but incomplete knowledge can hurt more than help. I need to have someone take care of this, I am willing to pay, but I have gone through quite a number of local HVAC companies, and none have left me in a situation I feel comfortable with - and each one has a completely different opinion of what the issues are and what kind of work the previous people have done.

Andy

Andy, I understand your frustration. Hydronic heat specialists are getting more difficult to find, I understand. Just be glad that you don't have steam. If you ever decide to replace the boiler, your engineering background might help. There a several variables and lots of calculations that need to be done to be sure you end up in a working envelope -- water temperature, heat loss from the structure, heat transfer via the radiators, circulation rate, temperature drop in the individual loops,... You could have a new hobby.

The boiler heads in those two fora will be able to help you out a lot, I think. Someone there, maybe several people, will know that boiler well. Just tell them you are tired of the excess heat and give them your boiler and indirect hot water tank details. Be sure to ask them about scheduling the boiler on and off when it is only needed for water heating. Look at that this way, if you have your boiler off 16 hours a day while working and sleeping during the week, and 8 hours on Saturday and Sunday, you've solved nearly 60% of your problem.

The flue can go in two ways and depends on what kind of boiler you have. There is subtlety that I am skipping. Condensing boilers have low temperature flue gas, and use plastic pipe going horizontally out of the side wall of the house. They are usually using outdoor air for combustion eliminating another heat loss point. Condensing the steam means heat recovery from that steam that used to leave boilers up the chimney. Now it runs down the drain after giving up its heat. All old fashioned residential boilers used to be non condensing. They will have a metal flue pipe that goes up to the roof line in some kind of double wall, insulated metal, or a metal joined to a masonry chimney.

The problem is a mismatch between boiler and flue. Obviously a high temperature boiler will melt/burn plastic pipe. I've never heard of that happening. Exhausting wet (and acidic) flue gas in a masonry, or inadequately corrosion resistant chimney will cause a much slower failure and that happens even though it should not. Particularly bad are very old, unlined masonry chimneys no tile liner. The acid gets to the mortar and eats it up leaving gaps. Sometimes, with a change to a more efficient condensing boiler, a plastic flue can be installed within an old-fashioned chimney and go up through the roof if going out sideways is not convenient or not eye-pleasing.

Okay, so a couple things. First of all, if the boiler is installed correctly and the baffles set up right, and the run of flu to the chimney is short, you shouldn't be getting that much heat in your room. Buderus boilers are 90% efficient and the flue temp should only be about 150 - 170 degrees. Maybe your copper pipe in the room leaving the boiler is just heating it up. You could try insulating the pipe.

There is a VERY good Buderus installer called Bender's Oil in Lebanon, CT. They put them in and send their guys to the training with Buderus. You could see if they have any guys who will drive up to Boston one day on the side, but I bet it will cost you. The issue with Buderus is that they are made by Bosch in Germany. The wiring, voltages, pipe threads...everything are metric and European standard. They do not work at all with American parts. You get some dimwit in there with a wrench trying to put U.S. fittings on your tank and he will destroy your boiler in no time. Buderus should be able to help you find a trained and authorized installer.

Secondly, you CAN seal the room up very tight, and insulate it....IF....you bring in outside air. Again, you have to account for wind load on the building and whatnot. Something to be left to professionals. If you tighten up the room without this you will backdraft your boiler.

We had a Buderus installed in our house when we will lived on the East Coast. It cut our heating bill by 75% over an old American single stack. When they are installed correctly and operating at full efficiency they are the best boiler on the market.

Super, if you now have a 90% boiler and are now saving 75% over your old boiler costs due to direct boiler operating costs, your old boiler must have been operating in the low 20s for efficiency. That is closing on open fireplace efficiency. Is that possible?

I'm not in that house anymore. We purchased it as an estate sale. It was an 1,800 sq ft colonial with an old 1960 single stack oil fired Arcoleader with the domestic supply tank in it as well. I got the heating bill records the last year the previous owner was in it. They paid $4,300 for one winter cycle, consuming around 1400 gallons of oil. I just about choked. We got a Buderus multi-zone model put in with an indirect SS tank, and broke our heating ring in half, one for upstairs one zone for main. We paid $850 for heat and domestic that first year, and slightly more the two years after that. The entire boiler and IDWH after some energy rebates was $5,800 installed. It paid for itself in two years. No brainer.

sometimes the boiler room will get warm...you have the piping radiating heat, you have the manifold radiating heat, etc. If you have a sealed boiler (combustion air from outside) there is no requirement for fresh air...I vent my boiler room (heat) via forced air ducting to the upstairs rooms that we keep cooler on purpose. The boiler room has vents as there is a laundry dryer in there.

In the winter, when this room heats up, the fan kicks on and blows air via a 10" duct to that farthest upstairs room...

in the summer, when the central air is running, the basement and furnace/boiler room get really cold. Same idea here, when that room and basement are 5-6° cooler than our main level t-stat setting (75°), the fan kicks on and forces cold and slightly damp basement air to that same upstairs room. The stairway path to that room is open. In short, hot air is forced up in the winter and cold air is forced up in the summer.

Andy - Any update on this? I live outside of Worcester and also have a hot basement. If you found someone who helped you, I would appreciate the referral.

https://heatinghelp.com/systems-help-center/why-you-should-insulate-steam-pipes/