Boiler fuel decision... Opinions

tbrooks

Hi guys. Been awhile since I posted, but I still lurk occasionally. My house is coming together, and now I'm finally nailing down how I'm gonna do my system. It's a retrofit, pipes above subfloor, plywood sleepers, aluminum plates, except garage which is slab. 8 zones and 2 manifolds. Total heat loss, right at 26k BTUs. And this is all diy install, I have siggy's book, and a good amount of plumbing experience.

So I have had my mind set for a little while now in a wood boiler. Was planning on a dedicated shed for it, plus I have a tractor, log splitter, pallet system for wood storage, and unlimited supply of logs from a local tree guy. I was contemplating a backup propane boiler later down the road for summer dhw and vacations or what not in the winter.
Now I've actually started looking into wood boilers, I am second guessing my self. Of course I don't really have a good grasp of what the options are, but the good ones I've seen are very pricey, plus the need for water storage if it isn't integrated.

Now I'm thinking maybe I should install a propane boiler, and possibly add the wood down the road when I have more money. Budget is a definite concern, although the boiler will probably be on credit for now, I'm already gonna have quite a bit of debt associated with the house. Propane boiler I can install in the garage, and it will save me a good bit just with it's location. And if it's feasible I even have a 50 gallon 63500 btu propane water heater I could use, even if it's just temporary. What do you guys think? My fuel choices are basically propane or wood, electric can be unreliable, and natural gas, pellets, and coal aren't readily available, and I've never liked the idea of oil from things I have read.

hot_rod

I would a start out with LP, shop for used wood stuff down the road. I recently sold a EKO 60 for $2500 with all the parts, pumps, flue, controls etc. Watch the boiler room at www.hearth for used wood burning equipment. You want a large buffer, proper controls and piping to do wood properly, it can be $$ to buy all that new.

Water heaters can be successfully used for hydronics, some brands are labeled for hydronic use, if an inspector should question. Make sure you run the tank hot enough to avoid prolonged condensation. I have seen tanks rot away the burner from running 100° constantly and condensing inside.

You have enough BTU in that tank to keep up with the load and cycle off, so it should be able to "dry out" inside.

EBEBRATT-Ed

Are you going to heat the garage where the boiler is located? Is the garage insulated or are you going to antifreeze the system? Is your 26k heat loss real? Your probably going to use the smallest mod-con available with a decent sized indirect for dhw

tbrooks

Thanks guys. So Bob, the tank sounds like it will work. Sounds like I should add a mixing valve to keep the temp up? My design temp is around 110. I will go to a real boiler eventually no matter what, but if I could use the tank for a year or 2, until I get some debt paid down, that would be great.

Ed, the garage will be heated, but I'm only planning on 50° in there. The garage is attached, and the total sq ft of the house and garage is about 1750. 26k btu is the total heating load, I actually paid for someone to do the heat loss assessment and piping layout, based on the information I gave them.

I knew from my own previous calculations it would be a small heating load, and that's part of why I'm second guessing wood, because it is way overkill for such a small load

Zman

It also comes down to what your time is worth. You can use the water heater but you are going to have to do it all over again to install the boiler. You can burn wood but who is stacking and feeding the beast?
Using wood to heat a well insulated house is a tough one. You have to keep the fire going even when the is no call for heat. Not so efficient...

This spreadsheet breaks down the cost per million Btu. Plug is the numbers and see how it looks.

JUGHNE

I did wood burning heating in my house as long as I had children to move the wood and did power line tree trimming that delivered chunked up pieces (to my size) to my back yard. (free BTW).
After that passed I just paid the gas bill and survived.

The wood will not always be "free".

If you enjoy working up firewood just go ahead and sell it to buy propane.
What would be nice though is to have a small nice stove for power outages and the ambiance a few times a year. IMO

Eastman

Is solar a possibility?
Here's a prepackaged system from caleffi:
https://www.caleffi.com/usa/en-us/catalogue/solar-water-heating-systems-prepackaged-nas30020

tbrooks

I hear you zman and jughne. It does seem like a lot more work all the way around to go with wood, and produce way more heat than I need. Then again, maybe down the road, I could find more uses for the heat to justify it. I always wanted to try and make a steam engine to run a generator lol. And I'm still relatively young so the work isn't that hard, but that won't always be the case. The way my system would work, I would have to cut up the right now free logs, use my vertical splitter on them right there, stack them in pallet crates I made as I split, and move the pallets to the wood shed. I had planned on a wood shed large enough to hold 12 cords, and it would be connected to my boiler shed. I was gonna put a large door on the shed and set the pallets right inside as needed. I could process all the wood for a season in a week I think, that's based on the 6 cords I used to use with a wood stove, it will differ with the boiler for sure.

I'm definitely leaning towards not doing wood for the foreseeable future anyway. It will also free up a 1/4 acre of land between the sheds and processing area. Long term I'm probably looking t 15-20 years for the wood to pay for itself, by then I probably won't want to do it anymore.

Eastman, it's not really. My neighbor has a row of pines just south of my house, I'd have to put them in the backyard and I don't really want that

Eastman

I feel like the HTP Crossover might be a good fit:
http://www.htproducts.com/RGH75100.html

hot_rod

tbrooks said:

Thanks guys. So Bob, the tank sounds like it will work. Sounds like I should add a mixing valve to keep the temp up? My design temp is around 110. I will go to a real boiler eventually no matter what, but if I could use the tank for a year or 2, until I get some debt paid down, that would be great.

Ed, the garage will be heated, but I'm only planning on 50° in there. The garage is attached, and the total sq ft of the house and garage is about 1750. 26k btu is the total heating load, I actually paid for someone to do the heat loss assessment and piping layout, based on the information I gave them.

I knew from my own previous calculations it would be a small heating load, and that's part of why I'm second guessing wood, because it is way overkill for such a small load

I have done many HW tank radiant LP and electric for both small systems, nice buffer, and folks on a tight budget. Certainly not the most efficient method, but fine until you get a final plan.

Solid_Fuel_Man

To burn wood efficiently and properly a significant amount of controls and storage are needed. Think used propane tank of 500gal or more.

That said, I have a super insulated 3,200 square foot house and heat DHW&house with 3 cord of hardwood annually in Northern Maine, with -40F design temp. 4 person household. I bought my gasification boiler new on Craigslist, but searched all classifieds for 3 years to find it.

As @hot rod said a water heater is certainly not the most efficient way to do it, but it will work and the price is right! Can buy you time to get what you really want. Burning wood full time is not nearly as much work as it's made out to be, but you must see the cost benefit and enjoy the physical labor to do it.

I build one fire a day: load wood, light it, close the door and walk away. Literally 5 min a day, all inside and I do it in my slippers. But I have a lot of money and time invested to get here, but it's all smooth sailing now. Very little work with the right setup. But I do it for a living.

This is my daily amount of wood for an above zero 24 hour period.

tbrooks

Well, I'm not sure exactly what I'm going to go with for a boiler, but I know it will be propane now. My budget to finish the house just got shot, as they finally came out to get my new well done after waiting 7 months. Totaled more than double what I had planned, plus I have only worked 2 weeks in 2 months. Good news is we have lots of work on the way, plus I've got a lot done on the house lately, almost ready to install the heated floors. But, I probably won't get the boiler til the end of summer.

I don't think I'll bother with the old water heater. I don't like the idea of plumbing all the components for it, just to change it later for a boiler. I don't think i mentioned it before, but I wanna do the dhw off the system as well. I have been researching boilers though. Seems there are some arguments against the he boilers, that they require more maintenance and have a shorter life than the cast iron. That in itself can negate the efficiency savings. Any comments on this? I will search on here about it too, but if anyone knows a good thread, point the way. Thanks

JUGHNE

You sound handy enough to do the maint on a ModCon.
One disadvantage of the CI is most will need combustion air brought into your house by some means.
And usually a "B" type vent thru the roof.
Another is lack of modulation of burner firing.

There is a thread here concerning the debate.....must be 5 pages or more long by now.

Brewbeer

Your heating load 26K at design is quite low. A boiler that has the ability to match loads less than 26K would be nice to have. What cast iron boilers run this low?

Regarding the efficiency savings of the mod con vs. cast iron and lifecycle costs in general: with your low load, you won't be burning a lot of fuel to begin with, so savings from higher efficiency aren't going to be large. For example if you use $1,000 worth of fuel per year, a 10% more efficient mod con might save $100. If total lifecycle cost are your decision driver, it's hard to see how the mod con would be less expensive. But if non pecuniary considerations are important, you may decide the mod con has more advantages.

tbrooks

Well I think the most important factor is comfort, close second is proper and efficient design. Maybe propane just isn't the best choice for such a small heat load. I know electric can go to lower BTUs. I just don't like the idea of depending on the grid for heat. I'd have to come up with a backup source of heat or power, in case we have a long outage in the winter

JUGHNE

You would need power for any boiler unless you go standing pilot with powerpile generation and gravity water flow.....not to likely with in floor tubing. Back to the small wood stove or LP fireplace vented thru the wall needing no power.

tbrooks

Yes, but needed 10a of 120 vs 40a of 240 is a big difference, especially when my gen is only 7k watts. I would have to get a 10k just for the boiler possibly, depending on what I end up finding

JUGHNE

You need clean power with good sine wave characteristics for anything containing computer boards. FWIW

tbrooks

Good point, as everything has computer boards now days. Think it's time to start a new thread.