Tankless propane fired water heater for in-floor radiant heat plus DHW.
Last Post 02 Dec 2014 09:02 AM by sailawayrb. 30 Replies.
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jmagillUser is Offline
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01 Dec 2014 10:45 AM
I have been using a tankless propane water heater for in floor radiant and DHW for 12 years now.

Yes, it can be done. Yes it works.
NRT.RobUser is Offline
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01 Dec 2014 11:00 AM
Unless you have a situation where you have really long, sustained DHW demands, or you have a situation where the house is largely unoccupied, there aren't many cases where on demands are the right choice for space heat or for domestic from a lifecycle cost perspective. Stainless Steel Mod/Con boilers, Con or Mod/con Tank heaters, or cheapo tanks are really the best answers if anything beyond first cost matters in most cases. Water temp requirements, fuel cost and prevailing heat loads/domestic usage loads drives the decision.

There are many reasons why. Reset water temps, potable separation, lower maintenance requirements, better efficiency, lower first cost, it all depends on which comparison you're making... but I haven't yet found a situation where an on demand was the best choice.

Doesn't mean it can't be done. Just means it's not the best choice. I've designed systems for tankless units too. I just don't recommend them, because they don't hit a sweet spot of any kind that I can see once maintenance is taken into account.

Basic rule of hydronics: complex combustion equipment performs best isolated from potable water streams. Potable water streams all too often have stuff in them that, over time, very often, drives more maintenance than any closed system should.

Might you get lucky? Sure. You might get lucky. Or you can do something else that doesn't require you to be as lucky.
Rockport Mechanical<br>RockportMechanical.com
sailawayrbUser is Offline
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01 Dec 2014 11:56 AM
Yes, it is commonly done and does work for a period of time. It might even be the best ROI option too, especially if you are not going to stay in the home very long. However, Rob is correct that it isn’t likely the best option for longer term operational/maintenance cost.
Borst Engineering & Construction LLC - Competence, Integrity and Professionalism are integral to all that we do!
jmagillUser is Offline
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01 Dec 2014 12:18 PM
ROI is good. No real need for high tech water mixing controls or resets. Works well for someone who likes to know the ins and outs of their own heating system. I could replace the heater every 5 years and be ahead because I can do it myself and not need expensive service calls. I know that because of caretaking a home with a boiler system. Caveats are that this is a system that if you are selling your house may be a problem for the new owners. I also believe that it works better in radiant floor systems with some mass. It also works better with a system where you don't set back the temp.
sailawayrbUser is Offline
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01 Dec 2014 12:39 PM
Yes, I would agree with this perspective. A lot of DIYers who use our free design software go this route and tell us that they are very happy with the results. Or perhaps the opening statement on the design software section of our website best conveys this:

“Often times you have to do a project yourself to obtain the best value and achieve 100% personal satisfaction. We are do-it-yourselfers (DIYers) at heart and we support like-minded people. We also believe that being self-reliant and building energy efficient homes that use renewable energy resources in a responsible manner is a good philosophy for our planet. To this end, these calculators were developed to enable everyone who shares this philosophy an opportunity to accomplish this.”
Borst Engineering & Construction LLC - Competence, Integrity and Professionalism are integral to all that we do!
BadgerBoilerMNUser is Offline
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01 Dec 2014 06:41 PM
And, most adults get what they deserve.

We get more calls to correct "open" systems--sometimes at the point of sale, and sometimes after, as with my niece and her husband, at Thanksgiving.
Two young mechanical engineers whom couldn't figure out why the basement level and garage in their new/old house would not heat up. After looking at the pictures we concluded the pump had failed and since the system was likely not winterized the garage slab is probably cooked as well. Of course the system would be a little confusing to winterize since the space heating and the potable DHW heating are mixed up with an electric water heater and a electric boiler (not suitable for potable water).

Open systems are just silly and attract those who want something for nothing, like free software for example...

Rob is right, without reservation.

What a breath of fresh air!

Thank you Rob!
MA<br>www.badgerboilerservice.com
sailawayrbUser is Offline
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01 Dec 2014 10:01 PM
Presumably and hopefully Jmagill is discussing a tankless combi and NOT just a tankless that he is using as an open HR heating system... Open systems should NEVER be used unless you want to play Russian roulette with your family.

Badger, it sounds like your niece and her husband should have attended a real engineering school. Those online diploma schools are cheap and tempting, but actually getting an education can be sometimes be worthwhile. You also can't get a State PE license without first going to an accredited school, getting 5 years of engineering experience, and passing the State engineering board exams.
Borst Engineering & Construction LLC - Competence, Integrity and Professionalism are integral to all that we do!
ChrisJUser is Offline
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02 Dec 2014 07:24 AM
" getting an education can be sometimes be worthwhile." Hopefully you speak better then you type.

I wish you would give it a rest...

sailawayrbUser is Offline
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02 Dec 2014 08:45 AM
No, I am the typical engineer and communication skills are certainly not my forte.

I would love to give it rest, but unfortunately we are on our own and have to police this forum ourselves. That means challenging statements that are clearly not true. I wish we had more people on this forum who actually truly advocated and shared green building knowledge instead of using Republican politics to emotionally sway opinion away from the truth. Nevertheless, such are the state of affairs and I don’t always get my wish.
Borst Engineering & Construction LLC - Competence, Integrity and Professionalism are integral to all that we do!
BadgerBoilerMNUser is Offline
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02 Dec 2014 08:51 AM
Clearly one of your personalities is an engineer. Let him out!

Both graduates of NDSU, thank you.

You missed the point as usual.

Speaking of police. Is there a nanny in the house?
MA<br>www.badgerboilerservice.com
sailawayrbUser is Offline
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02 Dec 2014 09:02 AM
So what exactly is your point Badger, and where exactly do you think we disagree?
Borst Engineering & Construction LLC - Competence, Integrity and Professionalism are integral to all that we do!
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