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Community and Q&A

Grundfos pumps in a radiant floor heat closed loop system

1familyonthego | Posted in Mechanicals on

Hi, we have an off-the-grid cabin in the mountains with hydronic radiant heat in the floors. The heat source is a combination solar and a Takagi JR heater. We’ve switched it to a closed system with a heat exchanger and glycol in the floors since we aren’t up there all the time in the winter. We have 4 zones with between 1 and 5 loops of 300′ of 1/2″ PEX depending on the zone. The existing pumps are Grundfos stainless steel low volume pumps (sorry, don’t have the model number but they were installed in 2007). The pumps use enough energy that running them at night during the winter is problematic. Are there any newer pumps that could work in this system that use less energy? Thanks!

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  1. GBA Editor
    Martin Holladay | | #1

    I know a few other off-grid homeowners who made the same mistake you did -- they installed a heating system that requires electricity to operate. All of these homeowners have abandoned their hydronic systems. One woman I know was almost in tears, because she had to run her gasoline-powered generator every night just to stay warm. The fuel costs were bankrupting her, and the noise was driving her crazy.

    You want a heating system that requires no electricity.

    There are only three ways to heat an off-grid house. The two most common are with a wood stove or with through-the-wall propane-fired space heaters that require no electricity. Empire makes several models of space heater that fit this description.

    If you prefer fuel oil, there is a third option: you can use an old-fashioned oil-burning stove that is fed by gravity. This will only work if you can install an elevated oil tank (higher than your stove). One manufacturer is Franco Belge, which makes the Napoleon oil-fired stove.

  2. 1familyonthego | | #2

    Thanks. We've been having a learning and growing experience on these issues ever since we bought the cabin last year. The number of DIY mistakes the builder made can at times feel overwhelming. But we've worked through a bunch. Anyway, one thing I didn't put in my post is that the cabin is a log home made with 12" fir logs out of Oregon. We've done a whole bunch of insulating and hole-patching so it is much more airtight than when we bought it. But with logs come challenges... I've been looking at the wall heaters trying to figure out if it is possible to vent through a log wall and I'm not sure it works. I was wondering if it might make more sense to put a freestanding stove or gas heater with a ceiling vent? Thanks for your help.

  3. GBA Editor
    Martin Holladay | | #3

    Yes, you can put a through-the-wall space heater in a log home. My buddy Bill has a couple in his log home. The manufacturer makes flue pipe extensions if you need them.

    It's also possible to buy propane space heaters that vent through the roof. My mother has one of those.

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