Basement Too Hot with Outdoor Woodburner

[oldachh]

Hello all,
I built my house in 2017 it’s a 2800 sqft 2 story. I installed an older central boiler 6048 when I built and it has been running amazing since I have installed it. I heat my hot water, forced air furnace and a hanging heater in my garage off of one loop. I monitor the temperatures with WiFi and all has ran very well the past few years. This year I finished my basement and I spray foamed the walls and did an accoustic drop tile ceiling that I thought would keep the heat above so the basement would level out. I have a zoned system and the basement is on it’s on zone but the issue I believe is the plex pipes running above the ceiling. When the rest of the house is 70 the basement is 77 and that is without the zone in the basement turning on at all. I am wondering what to do? I am thinking my options are to insulate the plex pipes in the ceiling, bring in outside fresh air to cool it down a bit( not ideal and I can’t use the furnace to do it because the heat exchanger is in there), or turn the temp down in the wood burner which it’s set at 185. Anyone have experience with this type of issue?

Thanks,
Henry

 

[dave_dj1]

How much uninsulated PEX is there? I wouldn't think that would radiate enough heat to get the basement that warm.
Is the furnace in the basement out in the open or in a small room? I have a similar set up but my basement doesn't have spray foam.

 

[oldachh]

The way the basement is I have 4 separate areas and the furnace is in one of them which is a closet. The walls are not insulated in there just on the exterior walls and the closet is in the center of the room. In the workshop area there is probably 75’ of plex/copper and above the main area with the thermostat it is probably 35-40ft. I am almost wondering if the basement is just that tight. The rest of the house is 6” walls spray foamed and is very tight, in fact it just dropped to low 30’s here and my other floors finally started calling for heat.

 

[oldachh]

Attached is a layout of the basement the bottom area is unfinished.

 

[schreib69]

You do not imply that you actually have the home built to use an "air exchanger" so I will assume it does not have one. If the home is really tight, that is, sealed so tightly hardly any fresh air gets into the home(only way to "know" is to have a front door pressure drop test done) occupants are not getting much fresh air. In Minnesota and lots of northern climes it is building code now to have some sort of "mechanical ventilation" and this mostly means new construction requires air handlers called heat recovery ventilator(HRV) or an Energy Recovery Ventilator(ERV). Their function is to bring in fresh air, filter it, and send it through a heat exchanger capable of extracting at least some of the heat from another stream of air coming from inside the home headed out. It is specified so that about 50 cfm of fresh air is introduced for each inhabitant. The objective is to keep the humidity from building up and to prevent CO2 from building up while drawing in fresh air with oxygen. Another way to know if you have a concern is to buy a CO2 sensor and measure concentration in your home. Ambient air runs about 400 ppm CO2; inside a home it is best to keep it below about 800-1000 ppm.
So, if you do not have mechanical vent control so far, you have an opportunity here:
-- install an HRV or ERV and upgrade your home for better fresh air and, at the same time,
-- use that hotter basement air to FEED the HRV with the hottest home air so as to maximize the rate of heating the cold, fresh air(in winter) coming in. This also minimizes the cost to heat that fresh air
-- This will help accomplish your main objective: Cooling down your basement.

Look into Panasonic ERV's if in the North country . . . one of the more affordable. Good luck.

 

[oldachh]

You do not imply that you actually have the home built to use an "air exchanger" so I will assume it does not have one. If the home is really tight, that is, sealed so tightly hardly any fresh air gets into the home(only way to "know" is to have a front door pressure drop test done) occupants are not getting much fresh air. In Minnesota and lots of northern climes it is building code now to have some sort of "mechanical ventilation" and this mostly means new construction requires air handlers called heat recovery ventilator(HRV) or an Energy Recovery Ventilator(ERV). Their function is to bring in fresh air, filter it, and send it through a heat exchanger capable of extracting at least some of the heat from another stream of air coming from inside the home headed out. It is specified so that about 50 cfm of fresh air is introduced for each inhabitant. The objective is to keep the humidity from building up and to prevent CO2 from building up while drawing in fresh air with oxygen. Another way to know if you have a concern is to buy a CO2 sensor and measure concentration in your home. Ambient air runs about 400 ppm CO2; inside a home it is best to keep it below about 800-1000 ppm.
So, if you do not have mechanical vent control so far, you have an opportunity here:
-- install an HRV or ERV and upgrade your home for better fresh air and, at the same time,
-- use that hotter basement air to FEED the HRV with the hottest home air so as to maximize the rate of heating the cold, fresh air(in winter) coming in. This also minimizes the cost to heat that fresh air
-- This will help accomplish your main objective: Cooling down your basement.

Look into Panasonic ERV's if in the North country . . . one of the more affordable. Good luck.

thank you, I will definitely look into that. When I was building I hired an HVAC contractor and I was the general, I know they have a duct going external to pull in fresh air because it is so tight, but I am not sure if the specs.

 

[Del_]

If you are not getting smoke in the house you most likely will be wasting your money on an air to air heat exchanger.

I'd start by insulating exposed copper pipes in the basement to lower the temperature. They lose many times the heat of PEX pipe.

 

[schreib69]

thank you, I will definitely look into that. When I was building I hired an HVAC contractor and I was the general, I know they have a duct going external to pull in fresh air because it is so tight, but I am not sure if the specs.

Yeah, I was my own GC too. Learned lots of hard lessons.
To keep things simple I installed two bath fans to function as the "mech. ventilation" to cheaply and simply satisfy the code and my inspector, but later decided it just makes sense to do it right and put in the ERV. If your HVAC sub simply put in a fresh air fan and nothing to take it out, that is not good, well certainly won't work correctly. If you are able to track down all that you have in your "system" and post it, I can make a more educated suggestion.
Good Luck.

 

[pdqdl]

It seems unlikely that your entire basement would be overheated by a couple of lines concealed by acoustic tile.

I suspect a problem with your zone controls and your air pickup. Some questions to answer:
1. Where is the air pickup/s located? Do you have a central return that feeds from each regulated zone, or is each zone regulated only on the incoming air duct. Is there an air pickup in the basement, and have you verified that it is functioning?
2. Are all parts of the basement equally warm? If you have an entirely hot basement, then that heat will have a source. Find the cold and hot areas, and you will know where it is coming from. A laser thermometer will find any hot spots from any hidden water lines connected to the boiler.
3. Once you have found the hot spots in the basement, now you need to figure out how to cool it. You might consider some old fashioned fans or other means of letting the hot air rise and the cold air down. Is there a door at the top of the stairs? Open it up! Hot air rises. You will get a continuous stream of air flowing up the ceiling and going down the stairs. This alone should equalize a great deal of imbalanced heat distribution.

You can trace your air flow by several different methods. Lighting a match and then blowing it out will produce a nice smoke trail, but it doesn't last long. My favorite way to track the air distribution of a house is to obtain a medium sized balloon filled with helium. Then weight it very carefully with paperclips, strips of paper and scotch tape or whatever. Make that balloon neutrally buoyant in the air, so it neither floats to the ceiling nor sinks to the floor. Then turn it loose in all the rooms and in the basement. Do the test with the furnace fan turned on and again with it turned off.

A well balanced balloon will generally end up stuck to the largest air intake in a forced air system. It may also do a continuous loop going up and down the stairs, too, or sometimes back and forth on a long hallway. That is usually a good sign of air exchange going up and down the stairway, or full length air exchange from the rooms to a central collection area.

Another thought: how much hot water is flowing through that furnace when the air circulation isn't turned on? That's a sure source of extra heat in the basement when the fan isn't otherwise distributing the heat. Obviously this isn't a concern if your zone control turns off the water to the furnace/heat exchanger when all zones are off.

Last thought: that hot water heater is a source of heat, too. It should show up as a hotter area in the basement if you do some careful analysis for hot spots.

 

[Del_]

My bet is that the wood boiler is the source of most of the heat in the basement. Plus the fact that your circulating pump keeps all of the plumbing at high temperatures running 24/7.

Does the WB have an insulated door?

I've read that turning down the boiler temperature can result in a corrosive condensate forming on the inside of the firebox, so I'd be careful about that. Look into it.

I'm not much on dumping heat outdoors if I can help it.

 

[pdqdl]

I agree. I kind of imagined an outdoor wood burner, since it isn't labeled on the diagram. I thought that the closet was holding the heat exchanger/furnace, with hot water pumped in from wherever the boiler is located. That closet doesn't look big enough to keep a wood burner, either.

 

[Del_]

The older Central Boiler wood boilers aren't know as being the most insulated. By bringing it indoors efficiency would have to be greatly improved as the heat lost in going into the living space. I wouldn't be surprised if the wood boiler doesn't lose 15% to it's local environment., the boiler room.

I wonder if the boiler room could be fan vented into the living space above?

Or maybe right into the duct work of the first floor?

It may need a check valve/damper so when the first floor air circulating fan kicks on that some of the duct work hot air doesn't enter the boiler room.

It sounds like a very efficient system.

 

[pdqdl]

That is pretty much the road I was going down. Find the heat source.

Here's another question: if that wood burning boiler is indoors, where is it getting the makeup air from? If you have a very tight house, that usually influences how well the burner works. If you don't have a tight house, and no "make up" air system, then you will find that the leaky corners of the house will be coldest, and will show cold air coming into the house anytime the burn chamber is sucking air up the flue.

 

[Del_]

It may be that having an almost air tight boiler room with an air input would reduce the amount of makeup air that is drawn in through various air leaks on the main floor of the house. If this air input in the boiler room is not closed though the house is going to exert a 'chimney effect' and draw air in through this vent. Unless of course if the boiler room were extremely air tight.

With stove vents, dryer vents etc it may be pretty hard to get the main living area extremely air tight. Of course to have 'healthy air' in the house a certain number of air exchanges per hour in necessary or else indoor air pollutants can become a problem.

I like the idea of a totally air tight boiler room with a damper on the input air to the boiler room or a way to get the hot air out of the boiler room into the duct work leading upstairs.

 

[oldachh]

Sorry guys I should have been more clear, let me clarify a couple things. My wood burner is an outdoor unit that runs hot water into the basement through 1” pipes from there it goes to a heat exchanger on the hot water tank and then to a heat exchanger in the plenum of the forced air furnace, then to the heat exchanger of the garage heater. All of these are connnected with 1” pex or copper pipes. The zone system I have is an arzel HVAC zone with a pneumatic damper on each duct of the furnace so every zone only opens when it calls for heat as they are fail close dampers. I like the ballon idea and will definitely try that. I have a laser thermometer too I will try and also have a temp camera at work I can borrow which should help.

 

[oldachh]

Yeah, I was my own GC too. Learned lots of hard lessons.
To keep things simple I installed two bath fans to function as the "mech. ventilation" to cheaply and simply satisfy the code and my inspector, but later decided it just makes sense to do it right and put in the ERV. If your HVAC sub simply put in a fresh air fan and nothing to take it out, that is not good, well certainly won't work correctly. If you are able to track down all that you have in your "system" and post it, I can make a more educated suggestion.
Good Luck.

It is just a duct that runs outside to pull fresh air into the cold air return. I am surprised if the ERV was code that I wouldn’t have had to comply in 2017, maybe it was after that?

 

[schreib69]

Some thoughts:
-- it may help to use a contact thermometer, like a regular thermocouple sensor or an accurate digital meat temp. sensor, to measure the room temps in the air, average 2 or 3 in each home level and compare that to what your T'stat temp sensor "says" the actual room temp IS. You want AIR temp. Doing so, tells you whether your damper controls in the air ducts really are telling what reality IS. if this is all fine, great on to other more likely things. . .
-- Do the same temperature sleuthing in your basement both above the ceiling and in the main room and compare to what the T'stat "says" it is. In other words verify your T'stat reflects reality. If it does NOT, relocate it.
-- it is likely, if you are correct that all this extra heat comes from the PEX above the bsmt ceiling, that placing an inch of styrofoam or fiberglas to retard heat transfer DOWNWARD into the basment air space could help. However, placing reflective foil on the topside of the tiles may be just as worthwhile. Reason: the highest temperature differential in your entire house is in the basement: between the internal PEX glycol temp and the living space. Because: It is at its highest incoming temp from the boiler and has yet to lose its heat. Much of the heat is RADIANT and can be reflected UP with reflective material.
-- It is ODD the heat is coming DOWN into the basement, heat rises. If you have carpet and padding above that retards(insulation) the heat flow into the 1st floor. Usually, heating contractors place radiant reflectors around the PEX under the 1st floor. Did YOURS?!
-- Run the dampers open more(increase temp settings) in the upper house levels and report in.
-- Go to the forum called "Heating Help: The Wall" and repost this. You will get folks who really know the business responding.

 

[Bill G]

The older Central Boiler wood boilers aren't know as being the most insulated. By bringing it indoors efficiency would have to be greatly improved as the heat lost in going into the living space. I wouldn't be surprised if the wood boiler doesn't lose 15% to it's local environment., the boiler room.

Where did you come up with that? First off it is a outdoor wood boiler. They are not designed to be placed inside a home. You say the Central Boiler brand are not known as being the most insulated. What makes you say that? What is your experience with them. How long have you owned one?

 

[schreib69]

It is just a duct that runs outside to pull fresh air into the cold air return. I am surprised if the ERV was code that I wouldn’t have had to comply in 2017, maybe it was after that?

or maybe your state has yet to implement code adopted in Minnesota, or inspector allowed it as a "pass" for the code requirement for "mechanical ventilation".

In any event, that is NOT what ASHRAE terms mechanical ventilation.
-- need both mech vent INTO the house and also taking it OUT of the house, at a minimum.
-- an HRV or ERV do this but also provide energy savings by reclaiming some of the heat going out.
-- two fans: one pushing air in and one out, do this, but reclaim NO heat lost from the stream exiting.

The other important thing to do, if you are serious here, is to have a home blower door test done.
https://web.archive.org/web/20041024182204/http://www.kcenergy.org/PublicHousing/BlowerDoorSteps.htm
also, this website and source is another great forum to help:
https://www.greenbuildingadvisor.co...-and-intake-and-exhaust-for-the-hrv-be-sealed

 

[oldachh]

or maybe your state has yet to implement code adopted in Minnesota, or inspector allowed it as a "pass" for the code requirement for "mechanical ventilation".

In any event, that is NOT what ASHRAE terms mechanical ventilation.
-- need both mech vent INTO the house and also taking it OUT of the house, at a minimum.
-- an HRV or ERV do this but also provide energy savings by reclaiming some of the heat going out.
-- two fans: one pushing air in and one out, do this, but reclaim NO heat lost from the stream exiting.

The other important thing to do, if you are serious here, is to have a home blower door test done.
https://web.archive.org/web/20041024182204/http://www.kcenergy.org/PublicHousing/BlowerDoorSteps.htm
also, this website and source is another great forum to help:
https://www.greenbuildingadvisor.co...-and-intake-and-exhaust-for-the-hrv-be-sealed

Thank you very much, this is helpful.