What Size Boiler?

Okay between the adimate boiler guys here, My father in law who is a plumber and HVAC guy and my brother who is a carpenter, I have been swayed to a hot water system. The house I am building will have a 1440 sq ft basement which will have the floor heated. Then the 1440 sq ft of living space which I plan on now heating with staple up radiant heat. I have used some BTU calculators which say I need about 75,000 BTUs. My Father in Law is saying 100,000 BTUs due to the amount of glass. What do you all think?

I think you need to do a heat loss, heat gain load calculation. A full HVAC Manual J calculation, not the abridged edition, because of the large glass area. Get your supplier of the radiant floor tubing to do a room by room layout. Total it all up and you will have your required BTU. Don't forget to add the domestic hot water heater load. Your father-in-law HAVC guy should know what I'm talking about.

Thanks Yanche. Yes he knew exactly what you were talking about.

or get an EFM boiler which is adjustable. You can tune it easily to exactly your requirements.

As Yanchy says , have the manual J calculations done. My place is an eight year old , well insulated ranch style home. I did the manual J calculations my self. I did it the long handed way. Very Very involved. A good HAVAC man will use computor software program (much faster). My house is 1700 square feet , with eight foot ceilings. My calculations come up to 35,396BTU's/Hr for the house itself(Basement not included). Lets say the basement is the same heat loss after manual J calculations. Now you're talking 70,792 BTU's/Hr. Your house is a little smaller than mine , and is being built new , according to code. I would have to "Guess" that 75,000 BTU's/Hr is more accurate. On the other hand , Howwww much glass are you talking about?? The only way to say for sure is ; Manual J Calculations.

There is nothing worse than having a heating system that does not,or can not, heat your home properly because it is just simply too small. You can't make a boiler produce more heat than it is able to make. But, you can make a boiler produce less heat than it is capable of making. So Why not just buy the bigger one ? That way you will know for sure you will have ample heat no matter the temp.

Cohiba8250; I can only think of 1 coal boiler rated much below 100,000 btu and that is the Keystoker KAA-2. You must definitely figure your heat loss but in the end you will probably end up with capacity to spare. I am partial to hot water heat and in floor is very nice. Have you heard of some of the new products out there for radiant floor heat? I know I found information a couple of years ago of flooring panels with aluminum sheeting bonded to it and pre-formed grooves to put the pex into. The grooves were in a universal type of pattern that all you had to do was be careful about how you laid them out and you were all set to snap in the pex and put your floor on top. It looked nice but I think it was marketed more for the western states.
Having a lot of glass will make a big difference on your heat loss. Standard double pane glass is only about an R-2 versus your walls at about R-19 or better. So called high performance glass that is energy star rated is only about R-3. There are some glass options that are even a bit better (higher R value) but you may find it cheaper to pay for the lost heat than the windows, at least in the short run. Another problem with the high performance glass packages is they are prone to degrade over time.
Good luck with the new house. If you choose coal hot water heat you will not be sorry.

Like KTM rider said, you can always reduce the output of the boiler. Even a hand load boiler will have a forced draft control system available. All the stoker boilers [recommended] will have some way of controling the BTU output.

With domestic hot water load, I'd go with the 100K BTU minimum. It is pretty easy to pull down the water temp in a boiler system with a load or two of laundry,and a hot shower with the house calling for heat.

I'm really envious.. a 14-1500 sq ft house, pluss the warm floor basement, new construction... heating with coal... Your cell phone bill will be bigger than your coal bill...

Greg L

I looked at some subfloor systems like wonder board. They are set up so your water temp is only 90 and they sure are expensive. That's why I decided on the staple up. Talked with my Father in law today and the load is 87000 BTUs. The great room is the heat leach as it has vaulted ceilings with glass from bottom to top. I think I'm leaning towards the Keystoker KAA-2 for the boiler and then also put a LL Econo in the Great room. Wish they still made the K-4. I haven't ruled out the Harmon 3000 yet just need to do some research and see if it's worth the extra $1000. I figure the LL Econo will keep it toasty on those really cold days where the wind is kicking and the thermo is at 10 or below. I had already decided on installing a small 7-10 KW propane standby Generator as it is common in the winter to have no electricity for 2-3 days. Wish I could afford a bigger one but I don't think the budget will allow for it. I checked on the township code and it is not a problem to have coal as your only heat source. I was up there this weekend and drove back Sunday afternoon. Between the wind and rain it was a fun drive.

Cohiba8250 wrote:Talked with my Father in law today and the load is 87000 BTUs.

I would go with 100,000 NET output as a minimum. Coal boilers are not always rated on output, some use the gross rating (input).

Your mortgage company will be the determining factor deciding if you can use coal as your sole heating fuel. If you are not going to have a mortgage, then you probably can get away with coal.

I would go with a slightly larger boiler, and skip the additional coal burner in the greatroom... With a vaulted ceiling, the hot air heat will just be on the ceiling.. With the warm floor, you will be toasty as long as you don't cover it with insulating carpeting. Keep it a wood or ceramic floor. Ceramic is best.

I've lived with various add on hot floor systems or built in hot floor systems for decades but only in parts of a house.. The floor heat is amazing, and a real luxury... My 40x60 shop has a water heated floor, very nice place to work. My new bathroom has a heated ceramic floor, I hate to leave the bathroom for the rest of the house.

Look into AHS and EFM boilers too. I'd lean towards a larger system, If you need more heat you can put in a 'Modine' heat exchanger to add hot air to the house... but I doubt it will be needed. You won't be limited if you slightly oversize.

Greg L

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Nope no mortgage. Even if I run slightly over budget, i could just do an equity loan using my land for collateral. You know I never even thought about not having any stove in the Great room. My mindset is wrapped up in the past with using wood heat. The house I grew up in we had a wood hot air furnace in the basement with a grate to let the heat rise and then a woodstove in the kitchen. Many a morning I woke up with snow on my blankets. Old farm houses didn't have the best windows. LOL It's hard to let go of old thought processes on solid fuel. The money I would have spent on the LL Econo would let me get the larger boiler and still maintain my budget. So maybe I need to be thinking 120,000 to 130,000 BTUs. BTW you guys have been so helpful with this part of my project!!! I'm starting to get excited as I gave my rough plans to the draftsman this weekend and should be applying for my building permit very soon. To think that 6 months ago I had planned on a propane hot air system! Sure am glad I talked to some folks and then found this forum!!

Cohiba8250 wrote:Nope no mortgage. Even if I run slightly over budget, i could just do an equity loan using my land for collateral. You know I never even thought about not having any stove in the Great room. My mindset is wrapped up in the past with using wood heat. The house I grew up in we had a wood hot air furnace in the basement with a grate to let the heat rise and then a woodstove in the kitchen. Many a morning I woke up with snow on my blankets. Old farm houses didn't have the best windows. LOL It's hard to let go of old thought processes on solid fuel. The money I would have spent on the LL Econo would let me get the larger boiler and still maintain my budget. So maybe I need to be thinking 120,000 to 130,000 BTUs. BTW you guys have been so helpful with this part of my project!!! I'm starting to get excited as I gave my rough plans to the draftsman this weekend and should be applying for my building permit very soon. To think that 6 months ago I had planned on a propane hot air system! Sure am glad I talked to some folks and then found this forum!!

Go with the KA-6 or see if keystoker will build the KA-4 for you . Or go with the Harman vf3000. The KA-2 uses a less robust stoker mechanisim . Still good but for a large boiler you would be better off with the K6 stoker mechanisim . Looking at it there isnt much that can go wrong .Plus if you ever add on to the house you will have the reserve .I have the Ka-4 and have been burning about 500#s /week . Thats with the domestic water and radient floor heat . Dave

I thought the Harman 3000 was a 95,000 BTU boiler? I need to find out how much the KA-6 is. I like the coal gun but hate how high the hopper is off the ground, plus at around $6500 with the options I want, the price is getting up there. Haven't checked out the EFM line yet but from reading here they seem to get pricey also. Wish I could find some efficiency ratings on the boilers so I could do a cost comparison. It would be worth spending more on the boiler if it's coal consumption was less.

Used reconditioned EFM's are between $25-3500. I think AHS has a summer special, last year it was $4500 for the S130.

Greg L