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optimistic
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# Posted: 11 Oct 2018 04:24pm
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Gosh it's been a long time since I wrote here...
Having a son and another one on the way slowed us down haha...
Still need to finish plumbing & electric before we can restart our weekend advantures.. Next next summer we'll rent a near by cabin for a couple of months so we can finish it up..
Slowly planning things. We have a wood fire stove in our 12x12 place but it dies quick at night so need to figure out better heating.
Had an idea - get those inexpensive propane tankless water heaters... Install it outdoor in a highly insulated box with vent. Run anti freeze fir hydronic heating in the system for it. Hook up circulation pump thermostats and so on and have cabin at night heat with that...
Two issues I see here are -
1. Incoming water temp to the tankless is high. And it isn't meant to be like that... I called one manufacturer and he thinks it's a none issue. I don't think so... Thought?
2. How to use thermostats.. Ideally it should be set to a temp then call fir heat. Tankless and circulation pump kick in and then when water temp is very high it should shot off tankless but keep pump going? I think that's how regular hydronic boilers work... It only kicks in the tankless again if temp isn't reached after a while or if water temp drop... Right?
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skootamattaschmidty
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# Posted: 11 Oct 2018 08:02pm
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I'm no expert but I'm pretty sure that that a lot of the tankless heaters have a run time of only
about twenty minutes then they automatically shut off which might pose some issues.
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ICC
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# Posted: 11 Oct 2018 09:09pm
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There seems to be a difference of opinion. I have it said that the idea is not good because, as you wondered, of the inlet water already being still quite warm, maybe hot. On demand heaters designed for making 40 degree water hot enough to shower with may not be able to safely operate with incoming being at 90 or 100, whatever.
I have also seen some Tagaki on demand heaters listed as suitable for in floor radiant heating. Maybe Tagaki has engineered some for that use?
What does your cabin use for making hot water? I have seen someone someplace make use of the hot water from an RV water heater to inside a small travel trailer, using a transmission cooler unit to release the heat to the trailer interior.
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ICC
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# Posted: 11 Oct 2018 09:10pm
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And the question about permitted run time is relevant. Continuous use like that might also shorten the life.
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Princelake
Member
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# Posted: 11 Oct 2018 09:34pm
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I worked in a home last year. The guy bought a massive tankless water heater ran lines all over the house and heats his home that way. It looked like a spaghetti factory in the basement. He said certain models are made to run continuously and others aren't. It's not a total crazy idea. Lots of homes have boiler systems
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paulz
Member
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# Posted: 12 Oct 2018 09:47am
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Interesting idea. What are the advantages over a conventiona gas heater? Effiency?
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Asher
Member
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# Posted: 12 Oct 2018 11:55am
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ever thought about building a exterior woodburning shed and just make a set up using a older model truck (all metal) radiator over top of the heat? Then just figuring out a pump to circulate the fluid? For a temp control you could use a coolant bypass valve from another car. It wouldn't be real accurate but a little trial and error you would probably find your setting...
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creeky
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# Posted: 12 Oct 2018 01:03pm
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The tagaki jr is rated for radiant floor/wall use. Don't know how it works but the price is right. Under 600.
One thing with radiant floor. The water is usually quite a low temp. So it may depend on the "low" you can set your water heater too.
Also be aware that the heat will come on very slowly.
For a 12x12 might be easier to install a small propane heater. Like this?
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sparky30_06
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# Posted: 12 Oct 2018 05:53pm
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the cheap tankless waterheaters will not work for hydronic heat.
1. they time out after about 20 mins.
2. (most important) they are not modulating. So they just have a set flame. On a modulating unit it will ramp up and down depending on the demand to make sure they water is kept at your desired set point.
Went down this road when thinking about replacing a boiler in my shop up north.
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cspot
Member
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# Posted: 12 Oct 2018 09:35pm
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My cabin is bigger, but I had the same problem as you. I installed a direct vent propane heater that doesn't need electric to run. It works very well.
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optimistic
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# Posted: 14 Oct 2018 09:02pm
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Thanks for the great replies. I installed the big takagi (199k) in my house in ny... works beautifully. obviously it is used as intended - for hot water but got me thinking... I actually want to replace it because I learned that they actually have a wall boiler that is wall hung like a tankless and will heat your house and your water... incredible..
Anyone else had lock with a small direct vent propane heater?
paulz - I just couldn't find a direct vent one that people were saying online that they are any good.. Seems like most are duds.
Asher - I will be in the same issue... needing to maintain a wood burning stove at night... and outdoor to boot? yaks. I was trying to see if they make a pellet outdoor one that is smart and you set the temp/thermostat and you are done.. but they don't
creeky - not sure I understood your low comment.. what does that mean? I thought I will be setting it to high and let it rip. The link you gave is one that I haven't seen before. I will try to read up on it.. so far most of the direct vent propane heaters that I came across had horrible reviews.
cspot - can you give a link to the one you got?
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optimistic
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# Posted: 14 Oct 2018 09:10pm
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before I forget...
I looked at this one: https://www.williamscomfortprod.com/product/high-efficiency-direct-vent-furnaces-2/
(way too expensive)
and this one https://www.williamscomfortprod.com/product/direct-vent-furnaces/
Which is less expensive..
I was surprised by their calculator though... I put my cabin size and info.. and it says I need like 20k btu.. seems right??
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optimistic
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# Posted: 14 Oct 2018 09:28pm
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Less thing... main reason for tankless idea:
hidden - tankless will be outdoor and I can hid radiators between joists of loft area...
That is beside the fact it will be accurate if I can set it to run.
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cspot
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# Posted: 15 Oct 2018 08:25pm
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Optimistic,
Here is the one that I bought.
https://www.northerntool.com/shop/tools/product_200631838_200631838
It is rated to heat 525 SF. No electric required, but if you do have electric then you can use the blower that is on it.
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