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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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lopet

I would like to set up a hot water storage tank in my shop and using my outdoor boiler to heat it. My problem is I can't get the water in the tank to circulate on it's own ( cold water at bottom and hot water on top ). It's a old electric heater with burned out elements, but I was told it will work. As all the drawings on line show two or three in and outlets on the the tank and one at the bottom I am wondering, if it won't work with this one, because mine only has one on top and one at the bottom.
I am also higher as four inches above the tank with the top of the  heat exchanger, as the whole thing is taller as the tank.
My question would be, is there any chance it will work when I bring up the tank and have the inlet on the top  of the tank level with the outlet on the exchanger ? Just would like to know before I waste any more time. ;D
I still have a small circulating pump left, which I have replaced for a bigger one years ago. It would force the cold water through the jacket.  Would that be a alternative ?
Must have missed that class in school.  ;D    Any advise would be appreciated.
 

 

The two white pex pipes indicate supply and return from the boiler. Black pipe is cold water supply from well. Short little white pex pipe feeds in to return line and is only to top up the boiler.

And I tried to rotate the picture and I am not smart enough for that either. ;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

Haa, I managed to make the picture smaller. It's in my gallery  if somebody can help me out.
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. !!

dustintheblood

Hi Lopet,

I've done exactly what you are trying to do.  Will send you a private message shortly with some tips and suppliers.

G
Case 75C, Case 1494, RangeRoad RR10T36, Igland 4001, Hardy 1400ST, WM LT40HD, WM Edger, ICS DH Kiln

lopet

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. !!

1270d

Should work, pipe your hot water into the bottom of the tank so it rises out of the top.

snowstorm

its to tall. i went through all this once. you have 3/4 copper running 11/2 copper thats fine but where it goes into the water heater it needs to go at the higth of the shut off valve. mine will run gravity with the 007 pump shut off and its 50ft from the manifold to the water heater

dustintheblood

With mine (which did work for years perfectly), the pipe leading from the top of the exchanger to the domestic hot water (in the tank) did not have that big bendy loop at the top.

The reason it works is that the hot water (in the tank) is heated and rises up and dumps into the top of the tank - pulling cooler water from the bottom of the tank - in a convection loop.

You may be able to try and insulate your top bend to kick start the convection, but it seems as though you're a bit high on that loop.

My exchanger length (placed vertically like yours) is only about 3/4 of the height of the tank.

Hope this helps.

If it doesn't I'll dig through some old files and find and then scan the documents that would help.
Case 75C, Case 1494, RangeRoad RR10T36, Igland 4001, Hardy 1400ST, WM LT40HD, WM Edger, ICS DH Kiln

dustintheblood

snowstorm wrote while I typed.  He's correct!

Good luck with it!
Case 75C, Case 1494, RangeRoad RR10T36, Igland 4001, Hardy 1400ST, WM LT40HD, WM Edger, ICS DH Kiln

lopet

Not sure what you mean by that.  The idea is to heat up the cold water in the tank by running the hot water from the wood boiler through the cooper jacket, but it won't circulate on it's own in the tank neither it gets warm.  Something is wrong , maybe I have to use cooper on top of the tank and not steel.
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. !!

snowstorm

my water heater is 47" tall the 3/4 copper is 46"then a 90 ell the 11/2 is 39"

lopet

My last post was meant as a reply to 1270d.

Snowstorm, we are getting back to my question in my first post. If I raise the tank about 18 " and leave the exchanger where it is and have the bottom fittings adjusted, on top use cooper fittings and go straight across back into the tank, you think it should work ?  To me it looks like the hot water coming out on top of the exchanger is fighting too much the cold water to get back into the tank.
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. !!

snowstorm

you have a lot of pipe an fittings there. why so many? i have the 3/4 going from the bottom to the top of the tank the hot from the owb goes to the 11/2 on the bottom and back to the manifold on the top. you have more than that

snowstorm

if its just storage couldnt you just go in the bottom an out the top? you sorta have it set up like a water heater

coxy

snowstorm is 100%   mine goes in the bottom comes out the top   and  I was told that the more elbows you have the harder it is for the water convection process

beenthere

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

1270d

Was on my phone and misunderstood.  Didn't look at the picture close enough either I guess.

lopet

And I am confused even more now. Maybe i should try to explain a little more detailed.
Yes it's just meant as a storage tank and the only hot water I've got, is coming in from the wood boiler at the bottom of the
1 1/2 cooper and goes back in to the return on top of the 1 1/2. Black pipe on the right is water supply from well and is te ed off for the future sink also pushes in from the bottom of the tank to keep it full. Another t is installed  from the well water leading into return line to the wood boiler ( short white pex pipe coming up from bottom). It's only meant to top up the wood boiler when it's needed and has a valve on it. ( maybe it's  confusing ). I have the same thing in the basement, but thought it's more convenient now, since I have water in the shop.
My problem is the tank ( old electric heater ) is only about 40" tall but the exchanger is about 56" tall and with starting about 4 " off floor it's about 20" taller than the tank. Theoretic I should have warm water coming out on top off the tank    (red ball valve). From there it will go to the sink and that's all I want , warm and cold water at the sink.
The boiler line who comes into the shop runs first trough a baseboard heater in the " office " and then through a couple of truck rads to heat the shop. And then from the return line I   t ed off the line for my storage tank ( white pex pipe coming from ceiling and going to the bottom of exchanger). Exchanger gets plenty hot, can't touch it but the warm water coming out of the 3/4 cooper on top is not going back into the tank. That's why I thought installing a small pump would force it through, but like to avoid it as it should run " on it's own ".
Hope I explained a little better and still hope for some more answers.
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. !!

coxy

did you put a bleeder on there may be it got some air in there I have also had trouble with air on my old set up had to bleed air out at least 2x a month

coxy

the more I look at it I think its got air to many elbows

tractorman44

Here is a site that will provide a lot of information on just the basic hot water circuit layout on conventional heating systems.  It doesn't show your EXACT layout, but it will show some good information on piping and how water should flow through the basic system.  It may or may not lead you to a conclusion, but it may be a good start. What the heck, it can't hurt !!!

http://www.miketheboilerman.com/pipeworklayouts.htm

r.man

Yours should work fine once you get the air out of the top bend. The elbows will slow down the thermo siphon but I expect speed is not a factor in the shop. The problem you may run into is the cold water choosing to travel through the sidearm when you try to draw hot water out.  My set up is similar to yours in piping and I installed a valve at the highest point in the house water side of the side arm to bleed off air. I have other fittings in my hot water tank which avoided a bypass problem. Worst case scenario for you is you may need to install a shut off valve in the side arm loop to shut it off while you draw hot water. Annoying but workable and you might not need it. Why aren't you piping the sidearm in with pex? Makes changes quick and easy.
Life is too short or my list is too long, not sure which. Dec 2014

lopet

coxy and r.man,    you guys think there is air trapped in those top elbows ? That's actually possible I think, as there is no bleeder on top. When I filled the tank, I had the valve open on top of the tank and let all the air push out of it, but most likely wouldn't push it through those top elbows. Good thought !!!!

I 'll be working on it again at the weekend , it's not a high priority thing.    Thanks anyways

tractorman 44   thanks for the link also, I will look into it and let you guys know, if there is any progress.
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

Quote from: r.man on February 09, 2015, 09:12:51 AM
Why aren't you piping the sidearm in with pex?

Well the reason why I used steel pipes  and unions is, that way I can shove  the whole thing around and the exchanger is kinda solid attached to the tank and also removable if necessary.   
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. !!

albirk

lopet 
You have a cold water heater that may or may not work lift the water heater and get the top of side arm as close to the top of the water heater as you can {extra pipe on the bottom} and a bleeder valve someplace on the cross run

lopet

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. !!

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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