Heat Loss Calculation / Boiler Sizing

Hello all,

I have a 1400 square foot (above grade) ranch on a windy hill in NY. It has a walkout basement, where my current oil boiler is. I moved in to my house in September, and since then have burned 350 gallons of oil. However, I have been keeping the house at 64-65 degrees while I am home, and 60 when I'm not home and when I'm asleep (I like sleeping in the cold, it's not some form of punishment ). The house is zoned as one large single zone, with two loops that the water makes. I am doing a bunch of plumbing work come late spring as I would like to add zones, as well as moving the copper runs away from the exterior walls of the basement to make room for walls. I plan on walling up the basement strictly for insulation value, and have no intention of placing living space down here. For DHW, I have an electric hot water heater currently. As there are only 2 people living in the house right now, my electric bills are very reasonable.

My house has less than ideal insulation currently, but I have just finished the rim joists with 2" thermax and foam and am moving to the attic next. I performed a heat loss calculation using one of the tools I saw posted here from builditsolar.com. Am I reading this correctly that I only "need" 38876 BUT/hr for heating? My current oil boiler his a 90k and has no problem keeping up, but it doesn't provide DHW. I have also just had a blower door test done and my house was found to be very tight. The contractor was recommending that I provide means for mechanical ventilation if I intend to do more air sealing and insulation, as I may get the house "too tight". I have attached my Heating Loss Results.

My goals for next heating season are to keep the basement between 65 and 75 degrees (it is currently about 53 no matter the weather outside it seems), and keep the house between 65 and 72 degrees. However, as you may have guessed by my joining this forum, I would like to look into heating with coal next season.

I am wondering if a VanWert VA400 would be enough for my heating needs, as well as DHW. I was thinking of adding a zone off the boiler for DHW, instead of buying the separate coil, and pre-heating the water that goes into my electric hot water heater using a heat exchanger. This would allow me to shut down in the summer if I wanted too (not sure yet) and still have my electric hot water. Also, in the future, I may be getting a hot tub. Is it practical to heat the hot tub water using a heat exchanger and a zone off the boiler? Would this move me out of a VA400 and into something bigger?



Thanks for your time,
Joe

Joe,

I can't help with numbers, but I'll say that making hot water can be quite a load on the boiler. There are several options for using your elec tank. Some more complicated than others. Here's a thread on that subject;

Truly tankless DHW from a coal boiler, is it possible?

I use "side arm" style heaters to preheat the water feeding the tank, and a loop from the boiler's coil heats the water when it's parked. Pics and blah blah in two posts dated 1-30-2011, page 3.

Also, whatever you do, I suggest valving your setup and placing a draincock so that you can flush the boiler's coil with ease.
Dave

Since you have had your infiltration verified as low, I would say your numbers are correct. Keep in mind this number is output needed from the radiators, not input needed to the system.

Keep your zoning to a minimum. One zone for 1400 sqaure foot ranch is not unreasonable. I would not go more than two per floor on that small of a house for standard finned tube radiation.

Add 10 percent to your number for safety. Add another 15% for pickup. Output from the boiler should be in the range of 49,000 btuh not including domestic water load. A indirect water heater or coil in the boiler would work for you.

A VA-400 is good for 100,000 btuh from what I can tell. This would be a good size boiler for you. I would not go larger unless you plan an addition.

I am wondering if a VanWert VA400 would be enough for my heating needs, as well as DHW.

The VA400 should be fine for the loads you have described. Thumbs up on doing your homework before buying a boiler. Dave has posted a link to a thread with good information on producing domestic hot water with a tankless coil and electric water heater. You could do the same thing with a plate heat exchanger or side arm heater if you wanted.

Also, in the future, I may be getting a hot tub. Is it practical to heat the hot tub water using a heat exchanger and a zone off the boiler? Would this move me out of a VA400 and into something bigger?

It all depends how quickly you want to get the hot tub up to temperature. If you intend to just maintain the temperature during "hot tub season" the VA400 and a stainless heat exchanger will work fine. There are several members on this board that heat large pools with their stoker boilers & a heat exchanger.

JRDepew wrote:The house is zoned as one large single zone, with two loops that the water makes. I am doing a bunch of plumbing work come late spring as I would like to add zones, as well as moving the copper runs away from the exterior walls of the basement to make room for walls.

Some people stay away from multiple small zones because it can cause short cycling. I have never found it to be an issue with coal boilers, especially with the proper controls. Your needs/preferences might be different than mine, but I think it is nice to have the basement, bedrooms, living area, and bathrooms on separate zones. I have six zones in my house, and I will probably add more this coming year.

JRDepew wrote:The contractor was recommending that I provide means for mechanical ventilation if I intend to do more air sealing and insulation, as I may get the house "too tight".

Your contractor is right. You may need to add some vents to the basement to allow sufficient make-up air.

Edit: One more thing...I want to point out that while a VA400 sounds like it is plenty of boiler for you plans, you don't need to limit your search to that particular model. A VA600 might be easier to find and will do the job also. If you like Van Werts, I suggest you talk to Arnie @ A & B and discuss the differences between the two models.

steamup wrote:Edit: One more thing...I want to point out that while a VA400 sounds like it is plenty of boiler for you plans, you don't need to limit your search to that particular model. A VA600 might be easier to find and will do the job also. If you like Van Werts, I suggest you talk to Arnie @ A & B and discuss the differences between the two models.

I have been looking at a bunch of boilers, and haven't limited my search to a specific model or type yet. I just wanted opinions from experienced coal burners on whether or not the VA400 would be big enough to do the job (and I'm glad that it is, as this opens up some options). I have looked at a VA600 that I passed on, and have been reaching out the feelers on an EFM 350 as well (I think this unit is rated at 160k btuh). To be honest, I have never used a coil burning appliance in my life, so I don't have a clue what type of boilers I like yet. Not sure if I would like auger fed or hopper fed more. I have 8 foot ceilings in the basement so height isn't much of an issue. What is an issue for packaging is that my chimney is in the center of the house, and since I have a lot of stuff in the basement, space is a consideration. Not a huge deal, but if a smaller footprint can do the job just as good, that would catch my eye. I probably won't be putting a coal bin in the basement either, so I am working out how I would like to feed the boiler. I do have plenty of room for an outside bin within 20-30 feet of the house, that should be easy for a truck to fill.

Any information on venting a basement so that I don't make it too tight? Is there a more sophisticated method than cracking the windows a little?

Thanks for all the info and opinions, keep em coming!

Joe

Here is a combustion air option:

http://tjernlund.com/combustionairintake.htm

note: the Keystoker KAa-2 and Harmon would be good size boilers also.

I prefer the auger-fed units because you can feed them out of a decent size bin and keep it at a reasonable height. I have seen people make wooden bins, use 55 gallon drums, used fuel tanks, 100 gallon water tanks, etc.

As for keeping the footprint to a minimum, the hopper-fed units win in that category...with Van Wert's next in line (short auger). One more tidbit about Van Werts...if you are looking at used ones, make sure the rings in the burn pot are in good shape. Last I heard a complete set of rings was around $500, and that doesn't include the top burner ring. They usually last a long time, just make sure you know what you're buying.

A Leisure Line 110 new boiler, with warantee, and including an oil gun for backup heat for long weekends away from home, or when on vacation is less than
$4000,, and that 's NEW..

Yet another boiler to consider.

Greg L.

The coaljack people have a boiler rated at 120,000 also. Royall also has a coal stoker.

My AA130 seems to handle part and low loads quite well. The AHS S130 is similar.

There are many to chose from. The more economical ones are hopper fed.

LsFarm wrote:A Leisure Line 110 new boiler, with warantee, and including an oil gun for backup heat for long weekends away from home, or when on vacation is less than
$4000,, and that 's NEW..

Yet another boiler to consider.

Greg L.

That is a very reasonable price on a brand new boiler. I would be keeping my current oil burner and tying the new unit into the current system. Is the system cheaper without the oil gun? Or is that considered part of the package?

How complex/reliable is the stoke unit on these? I know that repairing a stoker on an auger unit can get expensive, but I don't see much about them failing.

Thanks,
Joe

Greg,

Where are the LL110 boilers available for under 4k? The prices I have been getting are around 4400.

Thanks,
Joe

I'd call Leisure Line direct, I may be off a bit on the price, but I think it's around $4K.. I'm not sure what the price break would be for deleting the oil gun.

Greg L

LsFarm wrote:I'm not sure what the price break would be for deleting the oil gun.

I asked Matt about that when the LL110 was first introduced, he said it would be about $100 less without the oil burner. LL gets the boilers from Axeman Anderson as a packaged unit, so they end up with the oil burner regardless.

The LL stoker is very simple and reliable.

JRDepew wrote:Greg,

Where are the LL110 boilers available for under 4k? The prices I have been getting are around 4400.

Thanks,
Joe

Joe,

That price is real close to what I paid for my WL110K with the 5 GPM DHW coil and Easy Clean Out options. I ordered in Nov and took delivery a few weeks ago.

Dick

Thanks for all the advice everyone. I went up into the mountains last weekend and picked up an EFM350 from Dave at AES. The unit needs a little cleaning up and all the gaskets replaced, but the boiler looks to be in great condition.

So, does anyone know how much 1/4" rope gasket, and how much 3/8" rope gasket I need? It is a round door boiler.

Does this rope from McMaster look okay?

http://www.mcmaster.com/#rope-seals/=hci8qu

#8818k44

I was thinking about sealing the boiler to the base with Permatex Ultra-Black, but can I do the divider plate in the base with this as well?

Thanks,
Joe