OWB ? House too warm

[hupte]

I thought a water boiler heated up a huge amount of water so you didn't necessarily have to have long burn times? Once the whole tank is hot, the fire can about go out and you still suck heat from the thermal mass of all that hot water.

Anyway, new heater during shakedown, feed it a lesser amount of wood, or shoulder season wood. A lot of people would love to have that problem to solve, plenty of heat! Better than the opposite, never get enough heat!

the reason owb's hold huge amounts of water is so if your late filling it the thermal mass of the large volume of water will give your house some more heat for an extended period of time. hence allowing you to wake up at noon to fill it rather than waking up at 7am to fill it, for example.

feeding an owb some shoulder season of wood won't help to keep the house cooler. it will just burn the wood to get the temp up to 180*F until the aquastat is satisfied. however burning shoulder season wood during shoulder season weather in an owb saves your good hard wood for the colder months.

 

[NSMaple1]

I would either do the 3 way valve, or primary/secondary with a second pump. A system relying on manually controlling it is asking for issues if the person running it doesn't fully understand it, gets tired of tending it, or forgets to.

 

[hupte]

here is a pic of a bypass for a plate exchanger for DHW. the purpose of this is to divert the domestic water and prevent it from running thru the plate exchanger during summer months. but its a pic of a bypass none the less.

 

[hupte]

I would either do the 3 way valve, or primary/secondary with a second pump. A system relying on manually controlling it is asking for issues if the person running it doesn't fully understand it, gets tired of tending it, or forgets to.

I agree. if I was setting this up for myself I would go with a 3 way zone valve and a bypass. you would have to buy a transformer to control the zone valve, but it would require no option of human error. then have a thermostat control the zone valve and run thru the bypass normally. then when the temperature drops to say 70*F the bypass opens sending water thru the HX, then if the temp continues to drop. say to 68*F then the blower for the furnace kicks on.

 

[hupte]

But couldn't you manually just keep opening / closing the heat ex. bypass manual valve until you reached your desired temp. Yes I know it would be a pain in the ass, but should be possible without any extra wiring thermostats, and only involve installing 3 valves 2 adjustable valves and a one way check valve.

yes you (he) could. usually what I do with mine is bypass the heat when the temp will be 70 degrees outside for a high. but my house is bigger and less energy efficient. just gotta make sure I shut off the furnace blower too.

 

[AIM]

I'm bettin there is something going on with the tstat in the house. I'm also bettin it's something simple. Someone else suggested she possibly had the fan set to "on". This sounds like a good possibility.
The outside portion of the OWB is completely irrelevant to the problem. I don't care if the unit is the size of a semi truck and trailer designed to heat 50,000 sq ft. Doesn't matter... Only x amount of 170° water is gonna flow through the lines no matter what the unit is that is pumping it.
The furnace fan in a forced air setup is the ONLY thing controlling the inside temp. Water running 24/7 through the lines and exchanger alone won't overheat the place.

 

[lindnova]

yes you (he) could. usually what I do with mine is bypass the heat when the temp will be 70 degrees outside for a high. but my house is bigger and less energy efficient. just gotta make sure I shut off the furnace blower too.

That's what I do with mine, but I only have this problem when it is 70° also.

The less messing around in the furnace room the better. Since this problem affects them all the time it should be fixed properly; at least for peace of mind. Adjusting valves would be ongoing all the time and never be quite right.

A lot of good information in this thread!

 

[Oxford]

Well, you're half right. The only way to add heat to the house through the air handler is air flow, which can come from forced air movement via the fan OR from air movement induced by passive convection, where the less-dense air warmed by the constantly hot exchanger rises throughout the ductwork. This can be quite significant, and is exactly what is happening here. I have never seen a house heated by an OWB that is piped according to the manufacturer's examples- where there is constant flow through the exchanger- that was not overheated. The typical attitude of the owner is "I like it when my wife wears less clothes" or "God wants me to burn 20 cords of wood to heat a 1500 square foot house for four months because 'merica and anyway, I like cutting wood" or some such.

 

[Oxford]

Also, @AIM, there's nothing wrong with the stat.

 

[NSMaple1]

I'm bettin there is something going on with the tstat in the house. I'm also bettin it's something simple. Someone else suggested she possibly had the fan set to "on". This sounds like a good possibility.
The outside portion of the OWB is completely irrelevant to the problem. I don't care if the unit is the size of a semi truck and trailer designed to heat 50,000 sq ft. Doesn't matter... Only x amount of 170° water is gonna flow through the lines no matter what the unit is that is pumping it.
The furnace fan in a forced air setup is the ONLY thing controlling the inside temp. Water running 24/7 through the lines and exchanger alone won't overheat the place.

We don't have any idea on the plenum & ductwork setup, or heat exchanger size - if it's set up for good convection flow with good up flow & not much horizontal flow, and a direct cold air return feed at the bottom, it could very well convect quite a bit of heat without the blower going. Which is usually a good thing, actually. Plus, this is a very small house.

Do agree that what is going on outside is irrelevant to the issue. It's the system design.

I will refine my suggestion - I'd do the three way valve, controlled by the existing thermostat. The valve would activate when the blower fan comes on, and the blower fan gets turned on by the thermostat. As mentioned above, you might need to add a 24v transformer. And maybe a relay, but likely not. There might be 120v valves, but 24v are much more common, hence the transformer. Shouldn't be an overly complicated or overly expensive fix to fix it right.

If you wanted to fancy up the controlling, you could check out controlling the blower fan so it only comes on at a certain cold outdoor temperature whereas the valve would to its thing whenever the thermostat calls for heat - but better stick to the first part first. This is a much better problem to have, than not getting enough heat.

 

[AIM]

If everything is operating as it should and the house got to 87° on a 15° night just through convection. The I suggest they should sell all of the heating appliances and go buy a candle. In the summer just open the fridge every hour or 2 for a couple minutes and that should do it for AC.

 

[Coldfront]

She just moved in Friday and I only built one fire so far Saturday night. I have more playing around to do with it to try and figure it out. I guess I can try setting the normal water temp down to 160° (factory setting is at 170°) and also the differential temp down where the draft opens and draft fan kicks on to 150° (factory setting is at 160°). I noticed in her basement there is a air exchanger hooked up to the heat venting also because the house is so tight to provide fresh air and mold control, I'm not sure how to set that yet either, it was turned off.

 

[lindnova]

I would leave the outside unit alone and fix it inside. You want the outdoor unit to stay up to temp to avoid moisture and condensation that will rust the unit.

 

[flotek]

I hate to be the smart Alec of the responses but what did you think was going to happen you are running a system rated for double that size house , 1000 sq ft is a very small home . Even a medium wood stove would run you out on that size house

 

[AIM]

Nothing would happen Flotek.
It does NOT make ANY difference to the inside of the home what is heating the water outside. Like I said earlier you could have a OWB the size of a tractor trailer rig and it will make ZERO difference. 170° water is still 170° no matter what the size of the unit. The only time the outside unit size affects indoor temp is if it's to small and can't provide enough hot water to keep up with demand.
When the unit is to big, like this one, the excess heat is normally just not used.
I'm not sure where this particular problem is but it's not outside.

 

[NSMaple1]

I hate to be the smart Alec of the responses but what did you think was going to happen you are running a system rated for double that size house , 1000 sq ft is a very small home . Even a medium wood stove would run you out on that size house

I would expect the boiler to spend most of its time idling, making creosote, then making smoke when it wakes back up again. It should not impact what is happening inside the house. An OWB is not a wood stove.

 

[NSMaple1]

I noticed in her basement there is a air exchanger hooked up to the heat venting also because the house is so tight to provide fresh air and mold control, I'm not sure how to set that yet either, it was turned off.

Air exchangers should not be hooked up to the heat venting.

 

[Coldfront]

Air exchangers should not be hooked up to the heat venting.

I did not examine it that closely it is probably not hooked to the heating vents. And I we did not buy the wood boiler it was there came with the house.

 

[Schinny]

is there 2 thermostats ? you said the wood thermostat is set at 72. Did both of them say it was 87 ??? if there are two thermostats how is it wired to turn the furnace blower on and not the natural gas ?

 

[cantoo]

Aim, I agree with your statements. I heat 2 houses using a Pacific Western OWB , big old beast that everyone tells me is too big. The firebox is 54" deep with a 24x24 door. I could put lots of wood in it but I don't. I could fill it full of bone dry hardwood and get it cherry red but I put poplar in it and only enough to keep the fire going. In the summer we burn crap wood and throw a stick or two of ash in just to keep the coals there so when it fires every other day there is still something to light.