Will my boiler be oversized it....

larryjbjr

OK, after reading a lot of the stuff here y'all got me to thinking about oversized boilers. Right now I don't think my boiler is oversized for my house but…

So here is my scenario, I have an old two-story farmhouse. With almost a full basement. The ground floor is around 1400 sq feet, the upstairs is 600 sq feet. The basement, at least the usable part, is about 1000 sq feet.

Currently I have a 20 something-year-old burnham boiler rated at an output of 107,000 BTUs. Now, that was installed over 20 years ago when none of the house was insulated and the basement had more drafts than you can imagine. About three years ago I bought the house and blew in insulation for almost the whole house. I also redid the basement and sealed it very well. I would say I have cut the heat loss in half. And I plan to do more this summer yet.

Now, I am planning to put a wood-burning stove in the living room on the ground floor and heat the ground floor and second story almost entirely with that. I figure it may not heat some of the bedrooms very well but that's OK we just sleep in them anyhow. So I was planning to use the existing boiler to just heat the basement.

So my question is this, if I do that my boiler will be majorly oversized right? I will be heating less than 1000 sq feet with a 107,000 BTU boiler.

But, I don't want to replace it with a smaller boiler because then it will not be big enough to heat my whole house when/if wood gets low or when I go out of town.

Any comments or opinions you all have on this would be very much appreciated. If someone can steer me in the right direction that would be great. Because I'm not sure what to do here. Or if I should do anything at all.

larryjbjr

Also, I did a heat loss calculation with the Slant/Fin app. And, with a 70° inside and a 20° outside temperature, it gave me around 38,000 BTUs per hour. Now, I confess that I did not understand everything it asked for. But I think I understood most of it and was able to fill it out pretty close. Though I did it based upon the upgrades I plan to do this summer/fall.

Gordy

The present boiler will be oversized. However if it's not needing replaced I would live with it until it does. Then focus on which way to go with a new one.

Where is your location? Is 20 degrees the design day for your location?

What type of emitters do you have? Baseboard, cast iron radiators?

The present boiler will short cycle with all the upgrades to the envelope.

larryjbjr

> @Gordy said:
> The present boiler will be oversized. However if it's not needing replaced I would live with it until it does. Then focus on which way to go with a new one.
>
> Where is your location? Is 20 degrees the design day for your location?
>
> What type of emitters do you have? Baseboard, cast iron radiators?
>
> The present boiler will short cycle with all the upgrades to the envelope.

I'm just a bit north of Milwaukee Wisconsin. What do you mean by design day?

Currently I have several cast-iron radiators and a couple kickspace heaters. I am planning to heat the basement with cast-iron radiators.

larryjbjr

OK, I think by design date you mean the coldest day of the year. Well on my iPhone I can only go down to zero. But it gets a bit colder than that sometimes.

Anyhow based upon a 0° outside temperature I would need 52,000 BTUs .

Gordy

Use -4 design temp Milwaukee.

Design day is not necessarily the coldest day of the year, but a low that can possibly be seen most heating seasons.

larryjbjr

Ok, I can not find any way to go below 0 on this iPhone app. Probably could just say 55,000 BTUs and be close huh?

Steamhead

This is a hot-water system rather than a steam system, right?

larryjbjr

> @Steamhead said:
> This is a hot-water system rather than a steam system, right?

Yes, hot water system

Gordy

My point with your existing Ci rads is a future HE boiler will benefit from the lower awt you should be able to use now that emitters are oversized for the load due to your envelope upgrades.

JUGHNE

IIWM, I would keep the existing boiler and use it sparingly as needed.
Someday in the future the wood burning and all that goes with it may lose it's allure for you.
Then shop for a new HE system.

One thing to prolong the life of your existing boiler is to be sure the returning water is 130 to 140 degrees temp. Lower will cause condensation in the boiler and drastically shorten its life.
How do you heat your DHW for sinks etc?

larryjbjr

> @JUGHNE said:

> One thing to prolong the life of your existing boiler is to be sure the returning water is 130 to 140 degrees temp. Lower will cause condensation in the boiler and drastically shorten its life.

I don't know how I can do that. I I have the aquastat set at 190° but the water seldom gets over 150°. The furnace kicks on and heats the house and shuts off without getting over 150° usually. I was looking into that last year and the general consensus was because my cast-iron radiators are so big they are soaking up the heat.


> How do you heat your DHW for sinks etc?

I have a propane water heater.

JUGHNE

Can you post pictures of boiler and piping around it, stand back to get it all in.

Gordy

You can use a 3,or 4way mixing valve to provide boiler protection.

larryjbjr

> @JUGHNE said:
> Can you post pictures of boiler and piping around it, stand back to get it all in

I'm too embarrassed to do so. Y'all are going to laugh if you see it.

I'm a first-time homeowner and I tried to tackle this by myself and I had no clue what I was doing. Even now I'm only starting to understand it.

But I will try to get my courage up this evening or tomorrow to take a picture of it.

larryjbjr

I have a hypothetical question.

If I were to buy a new boiler, what size would I need to get? Based upon design day of 55,000 BTUs per hour? Would I just need a 55,000 BTU boiler? I'm thinking it would need to be bigger than that. Right?

I am not planning to buy a new boiler, I'm just trying to understand how this is calculated.

Gordy

larryjbjr said:

> @JUGHNE said:

> Can you post pictures of boiler and piping around it, stand back to get it all in



I'm too embarrassed to do so. Y'all are going to laugh if you see it.



I'm a first-time homeowner and I tried to tackle this by myself and I had no clue what I was doing. Even now I'm only starting to understand it.



But I will try to get my courage up this evening or tomorrow to take a picture of it.

We are here to help. Doubt if it's the worst that's been seen here for sure.

Steamhead

larryjbjr said:

I have a hypothetical question.



If I were to buy a new boiler, what size would I need to get? Based upon design day of 55,000 BTUs per hour? Would I just need a 55,000 BTU boiler? I'm thinking it would need to be bigger than that. Right?



I am not planning to buy a new boiler, I'm just trying to understand how this is calculated.

55,000 would be the Net rating. The Input rating would be higher.

larryjbjr

> @Steamhead said:
>
>
> 55,000 would be the Net rating. The Input rating would be higher.

So with my current boiler having a net of 107,000 BTUs output then is it oversized already?

Also, again trying to understand this, do I only need enough emitters to put out 55,000 BTUs per hour then?

j a_2

Honestly your overthinking it...and that's normal, so don't take me wrong....Let it rip for a heating season and adjust from there...

HVACNUT

Whatever you decide to do, even though you said the home is well insulated, you don't want any pipes to freeze. It doesn't take much, and if the pumps aren't moving water, a pipe on an exterior wall with a draft will freeze PDQ. And its possible the stove will satisfy your heat thermostat, so you won't even know... until you do.

larryjbjr

> @HVACNUT said:
> Whatever you decide to do, even though you said the home is well insulated, you don't want any pipes to freeze. It doesn't take much, and if the pumps aren't moving water, a pipe on an exterior wall with a draft will freeze PDQ. And its possible the stove will satisfy your heat thermostat, so you won't even know... until you do.

Now that is wise counsel.

I'll definitely keep that in mind.

larryjbjr

j a said:

Honestly your overthinking it...and that's normal, so don't take me wrong....Let it rip for a heating season and adjust from there...

I've let it rip for 3 winters now. And it's been ripping cash out of my pocket for all 3 winters.....though it has been getting steadily better...

I'm just trying to figure all this out. If there is nothing more I can do, fine, but if I can make changes to help things out, I want to do that.

If my boiler is over sized, then I need to know so I can look into replacing it in the near future. If not, then I need to know so that I can let it go and look elsewhere.

Am I thinking right?

larryjbjr

> @JUGHNE said:
> Can you post pictures of boiler and piping around it, stand back to get it all in.

OK here are the pictures.

Let me make a couple of disclaimers.

1) most of this work was done on very tight budget, with very little understanding, and In the middle of winter.

2) I know there is a rats nest of wires around the pumps. Again, it was done in the middle of winter when I was trying to make it more efficient. I plan to fix all that before heating season this year.

3) most of my pex is non oxygen barrier. Again, mostly done before I understood the seriousness of the need for oxygen barrier. I plan to fix that as soon as the budget allows.



Now for the pictures:

larryjbjr

I'm really not liking iPhone....I cannot get it to upload the pics...Let me switch to my laptop....

larryjbjr