Hard to heat home

Benjamin_cc500

I have a 3200 square footage house with hot water base board heat, the boiler is a Benjamin cc500 wood/oil combo but I have a hard time heating my house with just wood, the temp sits around 160 degrees Fahrenheit but it does not produce much heat out of the baseboards. A couple ppl have told me that it’s my boiler but I’d like to know some other thoughts before I bought a new boiler. Also I just bought this house and it’s the first time using this type of heating system !

nibs

Is your firewood well dried, otherwise you are using a lot of heat to dry the wood in the furnace.

Jamie Hall

The information I have available shows that boiler as having an output range, running on oil, from about 107,000 BTUh to 120,000 BTUh, depending on the burner and the nozzle. It does not -- understandably -- give output for burning wood, since that is extremely variable depending on the wood used, the way it has been stored and worked up, and stoked. It's highly unlikely to be more than that on wood -- and quite likely to be half that.

First question: does the boiler heat the house satisfactorily running on oil? That will give you a ballpark idea as to the match of the heating system -- as a system -- to the demands of the house.

Second question. What is the calculated heat loss of the house? You can use the Slant/Fin calculator for that (it's available, for free, on Slant/Fin's site and is not hard to use). Without that information, we really can't make any judgement on whether the boiler is matched to the load.

Third question, then: how much baseboard (lineal feet) and what kind do you have? That will allow figuring how much heat, and at what water temperature, the baseboard can absorb from the boiler and give off to the space.

Fourth question: you note that the temp sits at 160, but you don't get much heat out of the baseboards. Is that the same when it is firing on oil, or does it work satisfactorily on oil? What differences are there between the two? Are the pumps running the same on either one? What is the return temperature from the baseboards?

pecmsg

That 160°

Supply or return temperature?

Also whats the delta between supply and return? (Temperature differential)

Benjamin_cc500

Ok with the oil and the wood going the same time you can keep it comfortable with a temp of 22-24 degrees Celsius but it takes a while to get it warm and the oil burner seems to be always firing a lot. I can not calculate the heat loss at this moment but it’s a big house but has a lot of rooms not very open concept! And for the baseboard it pretty much travels all around the outside cold walls of the house in the basement and up stairs! The Aquastat set at low limit 150 and high limit 170 with a diff of 20 that’s what the manual calls for but I have it turned up to 190 that seems to work the best! But would never reach that temp with just wood and I have dry wood and big fires!

Jamie Hall

Aye. But what kind of wood? There is almost a 2:1 range in the heat content of various common firewoods, and that does make a difference...

We still need a heat loss calculation for the house.

Benjamin_cc500

Spruce that’s pretty much all we have here! I’m use to a forced air furnace and I never had any troubles with a warm house before, I’m just not satisfied with this heating system, I don’t know if I should take out the hot water system and put in a forced air furnace, thanks for your help!

nibs

All wood will give off around 8600 BTU's per pound with a moisture content of 20%, this number is almost constant for all species.
Do the math, you will need a lot of well dried wood, especially since spruce is not very dense.

nibs

Oops, should have noted that 8600 btu's would be under perfect conditions, you would probably be lucky to get 2/3rds of that.

Brewbeer

The best way to get to the info that you need to solve/resolve this, is to do an accurate, room-by-room heat loss analysis and radiator survey. For the emitter survey, you need to measure the length of the finned portions of your baseboards, since it is common to run piping without fins in radiator enclosures.

Jamie Hall

Spruce, on a cubic foot basis -- which is what you can throw into the firebox -- is one of the very worst heating woods -- as @nibs notes, spruce is pretty light. Under optimum conditions, 16,000,000 BTU/ cord, more or less. So a cord of spruce is only slightly more than 100 gallons of oil -- or to go even farther, a solid cubic foot of spruce and a gallon of oil have more or less the same heat content.

Benjamin_cc500

So that pretty much tells me that hot water radiation is not gonna work for me even if I do get a new style boiler because of the type of wood I have

KC_Jones

Benjamin_cc500 said:

So that pretty much tells me that hot water radiation is not gonna work for me even if I do get a new style boiler because of the type of wood I have

I am confused as to how you are drawing that conclusion?! The hot water system is not your issue, potentially the fuel is, but I doubt it's either by your description. If you switch to forced hot air, what will you use for fuel? It doesn't matter what system you put in you need a fuel to power it.

If you have 160 at the boiler and by your description the baseboard isn't hot, you aren't getting the BTU's to where they need to be. Could you elaborate on the baseboard not getting hot comment?

With the amount of baseboard you describe I can't imagine why you wouldn't be able to heat the house.

Jamie Hall

The problem isn't hot water radiation. You yourself said that if the oil burner is running, you get heat. This really should be telling you that your problem is trying to run with wood...

Granted, your hot water system probably isn't running as well as it should. And your house may not be as tight or as well insulated as it should be. But your fundamental problem is you are trying to use a fuel source which just won't supply what you need, and it doesn't matter what kind of heating system you have -- that won't change.

Benjamin_cc500

Spruce wood is all anyone here in this place burns and I previously owned a house with forced hot air and all I burned was spruce wood and never had any trouble with warming the house. I get up in the mornings and the temp is down to 18-19 degrees Celsius and I go down to the furnace and the wood is still in and reading 160 degrees Fahrenheit on the boiler, then when I add more wood and open the drafter it takes like 2 hours to heat up the house comfortably

Jamie Hall

Physics and thermodynamics are cruel masters, my friend, and wishful thinking won't change it a bit. The numbers don't lie. Are you really comparing apples to apples? I doubt it.

But.. whatever.

Benjamin_cc500

I’m just wondering if the boiler itself is the problem iv been told that it’s my problem but before spending the money on a new boiler just wondering if anyone has dealt with a Benjamin cc500!

STEVEusaPA

How's it piped? Proper circulation?

Brewbeer

You are going to need the room-by-room heat loss analysis and emitter survey to size a new boiler. Also, post photos of you currently boiler, and your radiators. Are the radiators clean?

Benjamin_cc500

I can’t answer your questions, I don’t know anything about the system and the only pipes you can see is at the boiler the rest are covered up! I cleaned the baseboards in the basement but the ones up stairs are not dirty

Benjamin_cc500

I’m not home at the moment but I’ll get a picture later

nibs

Nothing wrong with heating by burning wood, you just need to be aware that you will need just as many BTU's as with any other fuel.
The energy density of wood is less than that of fossil fuels so you need to compensate.
Burn spruce by all means, just have lots of cords of nice dry wood.
Harbor Freight was advertising a low cost (Can I say under $20) moisture content reader.

ratio

Take a few pics of the boiler, showing the piping & pump(s); & a few showing a typical baseboard, with the cover off. Might want to measure the total linear footage of the finned part, too.

Re the heat loss, it's not too hard to make a reasonable guesstimate yourself using the Slant-Fin app for you phone, from the app store. It's time consuming, and a little tedious, but the app does all the cyphering for you, all you need is a tape measure.

Benjamin_cc500

Here are some pics

Jamie Hall

Actually, in a sense, it may be the boiler. I'll have a better feel for that if you can come up with a heat loss calculation for the house. You have mentioned that with the oil burner (or perhaps you meant with both the oil burner and the wood?) running, you can get the house up to temperature. This suggests that your radiation in the house is adequate.

However. As several of us have noted, you are burning spruce. Now there is nothing wrong with spruce as a fuel -- except that it takes a lot of it, by volume, to produce a given amount of heat. It occurs to me on looking at the boiler again that it may be able to produce its rated output when fired with a high energy density wood, such as hickory, ash or oak -- which, no doubt, is what it was tested and rated with. The wood fire box simply may not be able to contain a large enough volume of spruce at any given time to produce the heat needed.

So... as I say, in a sense it may be the boiler -- or perhaps more accurately, the combination of the boiler and the wood you are firing.

neilc

if you're 160 at the boiler, and the radiators are not 160 - 150, seems the circulator isn't running or doing its job.