Help with Designing Simple Hydronic System for Mountain Cabin

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  #1  
Old 12-08-16, 10:02 PM
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Help with Designing Simple Hydronic System for Mountain Cabin

Hello Everyone,
This is my first posting here, but I've been scouring this site for a while and finding some excellent help for my mountain cabin project. Thanks very much.

I've installed in-floor tubing for a hydronics system and want to make the boiler board over this winter. I've done all of the work on the cabin so far (excavating, septic system, footings/foundation/plumbing, electrical, etc.) but have zero experience with hydronic systems.

I'm interested in designing the simplest system possible, both because I have very limited space and for reliability. The cabin is at 8,415' in the mountains and will be completely powered down for long stretches in the winter. It is currently under 3' of snow and the inside temperatures are about 5 degrees Fahrenheit.

The floor heat is a glycol filled closed loop system and the hot water system is a completely separate on-demand tankless system. The heated floor area is 4 loops and 500 square feet on each floor for a total of 1,000 square feet. It is pretty small.

Does this attached schematic look like it will work? I realize I can make it much fancier, but am trying to make it as simple as possible. There is only one circulating pump and the different loops are controlled by adjusting full port ball valves.

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Thanks in advance for any help or insights.
 
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  #2  
Old 12-09-16, 07:28 AM
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You need a low-water cutoff and a backflow preventer.

I'm skeptical about the full-flow, wye-type strainer in the return line - what if it plugs? I would prefer a side-stream strainer. Is the check valve a lift-check to prevent gravity flow?

The relief valve should come off a tee in the supply line, right from the boiler.

Ball valves are not recommended for throttling flow-control. Globe valves are preferred. Personally, I think you are overdoing the number of loops for such a small space.
 
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Old 12-09-16, 03:46 PM
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More - the W-M boiler is a condensing type - not exactly conforming to your "keep as simple as possible" philosophy. Just a plain, non-condensing boiler would be simpler and require less routine maintenance.

You are committed to hydronic heat. But, my choice would have been electric resistance heat or a forced air furnace. I assume you have electric power available. Glycol can be a pain - to dispose of, to deal with leaks, and overall messiness.

You are planning to use propane. Make sure it will adequately vaporize at your lowest ambient temperature.
 
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Old 12-12-16, 02:29 PM
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Thanks gilmorrie. I'll look into a plain condensing boiler.

I've got a 1,000 gallon propane tank which fuels the radiant floor, tankless water heater and a gas kitchen stove. We do have electricity, but it is not always reliable, especially in the winter when it can be out for weeks at a time. Part of my reasoning for going with a condensing boiler like the WM Eco 70 was for its efficiency, as once we are out of propane... we are out of heat.

Andrew
 
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Old 12-12-16, 03:41 PM
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We do have electricity, but it is not always reliable, especially in the winter when it can be out for weeks at a time.
When your electric power goes out, your boiler won't run - unless you have a backup generator.
 
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