Design questions: Boiler outside and elevated above basement storage tanks?

[Downeast Farmer]

And how about all those buckets full of fittings?--Any idea what those came to? Total cost, in other words, if you don't mind sharing....

 

[maple1]

Me?

Haven't added that part up yet.

Admittedly kind of scared to - and it might break my calculator. I plan to, whenever I get around to it. I'm also still in the 'tieing up lose ends' stage - that could go on for a while. I seemed to have spent all my motivation in just getting it up & operating.

 

[Downeast Farmer]

I'm beginning to cost out an install; thus my curiosity. I'd guess you could easily double your storage costs with all those odds and ends. Getting it up and running, though, that's the place to spend time....

 

[leon]

I'm looking for your thoughts about how to design a pressurized system with the tanks located in the basement and the boiler about 5' above in an out building at grade level.

I'm still struggling with the concepts and price of a boiler for a new house and am in the design phase; I don't have a place for a wood boiler in the house. The house will be tight and very well insulated. I estimate the heating load at about 25-30k Btu on an 80 degree differential. To satisfy the bank, I'll need a propane, oil or electric heating system and will likely use propane with a mod-con boiler and baseboard. I also want to include a wood boiler because I have wood. Because the house is tight, the anticipated heating costs will be low, so fuel savings will be small and payback will likely be many (20) years, so using a wood boiler is not just an economic decision, but a decision to wean my home off fossil fuels.

I'm considering placing the boiler in an outbuilding and the storage tanks in the home's basement. What are the pitfalls and design considerations? How do I protect the boiler from draining into the storage tanks as the cooling water contracts? Can I use antifreeze to protect the boiler from freezing? Do I need an expansion tank elevated above the boiler to ensure the boiler retains water in is jacket? I assume that I'll need a boiler loop filled with antifreeze and a loop for the storage water (2 circulators) and just to heat the storage water. Am I on the right track?

I'd love to place the boiler in the basement but the dust & wood mess, smoke, combustion air and flue all present problems in a tight home.

Thanks for your thoughts....

John

About your issues with heat;

Installing a boiler in an outbuilding is good idea
in order to keep the mess outside of the living space,
but the placement of the heated storage in the basement
requires more work and time and there is always the
hazard of a leak.

If both the boiler and storage are next to each other the plumbing
will be more efficient and you can use the good insulated pex that
is 13-15 dollars a foot to deliver heat and return the cold water to the
boiler/storage.

If your going to build a tight house there is no reason you could not
use refurbished and cleaned radiators from a surplus building
materials business that specialises in used reclaimed items from
dismantled houses and buildings.

I heat with wood and coal and I absolutely despise my hot water
baseboard becuase it wastes heat and is miserable to distribute
heat because my house is so poorly insulated and when you
have wife that is hoarder..................


I plan on replacing my 32 year old boiler with a hand fired Harmon wood
and coal boiler and adding storage using at least 4 of the
New Horizons 490 gallon insulated storage tanks and changing
my pressurised system back to an open system.

Keeping your storage and the boiler at the same height reduces
the chance of pump failure because the pump or pumps will always
have flooded suction and having an open system eliminates the need
for a pressure bladder because the system is flooded and the water
is always moving. A second pump to maintain the temperature
between the two boilers (which I have) I think is waste of money
when you have a large thermal mass on the wood and coal side
or intend to as I plan on doing.

A number of very small converted steam radiators used for hot water
would (be positioned on the interior walls as they should be) require
much less plumbing and the total distance of piping would be much
less in total as the radiators would have thier own thermostats too
and the temperature would be regulated to each and every room.

A steam radiator converted to hot water can be elegant with a nice
radiator cover and be much less in cost per foot.

The more thermal mass you have the less costly a heating system
becomes to operate as the heat energy is stored by the thermal
mass in a huge quantity. A non pressurised system using a thermal
expansion tank without a bladder using an atmospheric air vent also
aids in considerable savings.

 

[maple1]

How does hot water baseboard waste heat?

 

[Beerdog]

Maple1...

I'm not sure I understand how baseboard "wastes" heat, but they are not as efficient at taking advantage of stored heat as radiant heating systems that operate at lower temperatures. I can think of two main advantages of systems that operate at lower temperatures:
1. A lower supply temperature allows for more energy to be extracted from a given volume of heat storage. When comparing to a system that can use 120 degree supply water, baseboard requiring 140 degrees means that the heat stored in the system below 140 cant be taken advantage of. This limitation requires the storage to be increased to supply the home with a given amount of Btus. If the supply temperature can be reduced to 120, then, assuming my upper limit is 200, we can extract another 20 degrees of heat, a 33% increase in Btus over the 200-140 degree operating range's differential of 60 degrees. This means that we can reduce the storage volume, and at the same time, or, for a given volume of storage, we can extend the time between burns. Of course, the burn times need to be increased to add the heat back into storage, but the increased time between burns allows us more freedom to do other things than to tend a boiler.

2. Operating at a lower temperature reduces the draftiness due to convection currents and high apparent temperature differences. Baseboard primarily operates on convection, not radiation and so it heats the air and creates air currents to move heat. I'm not sure there's an efficiency issue here.

3. From the standpoint of using a modulating/condensing boiler, lower supply temperatures are used to condense the exhaust's water vapor, resulting in the recovery of the heat of vaporization. This latent energy would have otherwise been lost without the ability to use the lower water temperature. An analogy is the cold water glass in summer where heat is taken out of the air by the cold water. The removal of the heat of vaporization from the air causes the water to return to a liquid state and condense on the glass. The heat recovered warms up the water in the glass. Condensation, i.e., recovery of the latent heat of vaporization that turned the water into a gas vapor, can't happen if the water temperature is too high. Lower supply temps allow for condensing boilers.

John