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A little off topic. Water to water heat exchanger.

Started by lopet, February 08, 2015, 06:45:32 PM

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albirk

lopet
one other thing that may help is to cut some of the 3/4" off and go with a 90 to help make it shorter

Al_Smith

The thermo/siphen idea worked pretty good on an old John-Deere A but you might have to think of a recirculating pump with this idea .There are a wide selection of those with some relatively inexpensive if you go that route .

From what I see using an outside boiler really isn't much different than using the water heating capabilities of some geo-thermal units .With that system it requires a recirc pump to work .

mapleveneer

It looks like what you are attempting to do is similar to a side-arm water heater.  Do a google search for that term and you will find lots of information.  I have one setup on my electric water heater and the thermo syphon works perfectly.  Water is much hotter in the winter when the boiler is operating that in summer when we are burning electicity.  The side-arm heater is really a shell and tube heat exchanger, domestic hot water in the tubes, boiler water in the shell.  I think that is what your 1-1/2 in. pipe is, correct?

Yes, the high point in the piping over the top of the tank is going to create problems.  You are asking the heated water to rise and then fall, it doesn't like to do that.

Probably your biggest issue though is the fact that the shell/tube heat exchanger is as tall as your tank and at the same level.  You will only really heat the water in the tank that is above the level of the heat exchanger.  My heat exchanger is maybe 12-18in. tall and located as close to the bottom of the tank as possible.  that way I can effectively heat the water in at least the top half of the tank.  One of my rainy day projects that I haven't gotten to is to raise the hot water tank so that it is actually above the level of the top of the heat exchanger.  That way the exchanger will heat the entire tank.

I know that it is a little hard to get your head around the concept of the exchanger only heating the water above its level but believe me that is how it works.  Once you have heated the tank water down to the level of the top of the heat exchanger things start to equalize and then the thermo syphon stops.


beenthere

mapleveneer

Your side arm is very similar to mine, except on mine the boiler water goes into a 30 gal stainless steel tank and spirals down through the domestic cold water which sits just ahead of (and supplies) the domestic hotwater heater.
Hot boiler water enters in the top, and exits the bottom (dropping as it cools to set up the thermo syphon). A air trap valve at the top which lets out any air bubble which will stop the thermo syphon.

Domestic cold water enters the 30 gal SS tank at the bottom and exits to the HW heater from the top.



 

south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

lopet

Got it working today, well kinda.  The main problem was air trapped in the top elbows, so you guys were right.  But I still want to built a stand for the tank and raise it about 18" as the water in the tank does not get hot all the way to the bottom ,but the top half  gets hotter then with electric. I am sure I can improve it more and will install a bleeder on top and a temperature gauge.  Will let you you know how it goes.

Nice setup too bt but mine is only meant for the wintertime and only cold tap water in the summer. ;D 
Make sure you know how to fall properly when you fall and as to not hurt anyone around you.
Also remember, it's not the fall what hurts, its the sudden stop. !!

lopet

Little update here.  I raised the tank about 16" and turned the sidearm upside down. That way I have the short end of the
3/4 on top of the 1 1/2 , then I came straight across and back in to the tank with no elbows.  Works like a charm and more hot water than I will ever need.
Thinking about doing the same thing for the house next winter.

Thanks again for all the ideas.


 


 
Make sure you know how to fall properly when you fall and as to not hurt anyone around you.
Also remember, it's not the fall what hurts, its the sudden stop. !!

WmFritz

Glad you have it worked out and thanks for the update.
~Bill

2012 Homebuilt Bandmill
1959 Detroit built Ferguson TO35

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