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Old 01-09-2020, 01:28 PM   #1
Skoolie
 
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Webasto to Radiant Floors - How to transfer the heat between systems

Hi all.

We are looking for a method of using the Scholastic Webasto to heat radiant floors in our bus. I saw on some past forums that, since the Webasto often reaches temperatures too high to heat radiant floors, that you should buy a compatible water heater with a heat exchanger inside to transfer the heat from the Webasto to the water heater. And then a separate heat exchanger to transfer the heat from the water heater to the glycol in the heated floors.

Is there a very specific variety of water heater that is capable of this type of heat exchange? (i.e. transfer heat From Webasto Heated Coolent, to Potable Water, to Glycol) What kind of key words should I be looking for? Is this system rarely discussed because of some other problem that I have not recognized yet?

Note: This general topic seems to have been brought up in the past, but I haven't found any answers that still have working links. Sorry if this is redundant.

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Old 01-09-2020, 04:54 PM   #2
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Originally Posted by Truffles View Post
Hi all.


Is there a very specific variety of water heater that is capable of this type of heat exchange? (i.e. transfer heat From Webasto Heated Coolent, to Potable Water, to Glycol) What kind of key words should I be looking for? Is this system rarely discussed because of some other problem that I have not recognized yet?
I can't answer your specific questions, perhaps I can help with what I have and works for me. I don't have a Webasto, I have an Espar.
I would think the heater would make water somewhere around 170° or so which is lower than what your engine makes. I used a heat exchanger similar to this. NOT this one in particular I think mine is 20 plate but, don't remember for sure. Do your own math.

https://www.amazon.com/Brazetek-Exch.../dp/B00401AIX4

It goes in the water lines from the engine that would normally go to the heater, the other end goes in the loop that your heater is in. It works both ways if heater is on engine is warm, if engine is running and warm heater loop is warm. I also have a marine hot water heater, in the heater loop, that has an internal heat exchanger.

I have been using this for over 5 years with no problems although some will say that engine temp is over recommended for pex.

There are some pictures here.

Heat
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Old 01-09-2020, 04:59 PM   #3
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My webasto is rated to turn off at 170 and back on at 158.. a heat exchanger like the one somewhereinusa listed is exactly perfect for floor loops.. you can turn the pump on and off if your loop temp gets too high and the webasto will simply cycle out when it reaches 170 in the heat exchanger...
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Old 01-10-2020, 03:36 AM   #4
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I have only seen one RV water heater that had a coolant heat exchanger built in. And I bought it....

There are a number of marina water heaters that have that feature.
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Old 01-10-2020, 09:54 AM   #5
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I have only seen one RV water heater that had a coolant heat exchanger built in. And I bought it....

There are a number of marina water heaters that have that feature.

Yup, Suburban makes one. https://www.dyersonline.com/suburban...d-sw10dem.html


I think Atwood might have one too.
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Old 01-12-2020, 05:01 AM   #6
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Yup, Suburban makes one. https://www.dyersonline.com/suburban...d-sw10dem.html


I think Atwood might have one too.
Thank you. I stumbled onto the one I bought for my first build at a surplus store. When I went looking for another one I couldn't find it.
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