Flat plate heat exchanger domestic water

[cantoo]

Ok got ya. So what is in the OWB that the water is heated with initially? Is it some type of "radiator" ? What kind of material?

All I am looking for is a a few loops of pipe, or a "radiator" that can be mounted on the outside of stove, that is in my basement, then plumbed in to in-floor heat loop before it gets to my boiler, to preheat or even not use boiler. Pump and expansion tank are all there, I just want to preheat.

I think maybe you are looking for something like on this site. Water coil.
http://www.hilkoil.com/

 

[tla100]

That is right what I was thinking. Thanks a lot for the link. Will check into it.

 

[Jake Wise]

I have been thinking about this and it seems to me that with a large enough flat plate exchanger you could essentially have a tankless water heater. It would heat up enough on the way through that it could be used an would have no need to sit in the holding tank of the dw heater.

 

[NSMaple1]

Yes, you could likely use a FPHX as an on-demand water heater.

But you would need a steady supply/flow of very hot water through the supply side. So if there are times where either the boiler cools off some, or the flow temporarily stops, you won't have hot water.

 

[lindnova]

With my outdoor furnace I could use mine like an on demand tankless, but I put mine before the tank in case I run out of wood (rarely ever happens) and I do need the propane heater for the summer when I am not firing the furnace.

 

[Joesell]

I have been thinking about this and it seems to me that with a large enough flat plate exchanger you could essentially have a tankless water heater. It would heat up enough on the way through that it could be used an would have no need to sit in the holding tank of the dw heater.

I have endless hot water with a 20 plate.

 

[Guswhit]

I installed a sidearm on mine, then had 2 girls added into the family. Between all of the laundry and baths I was running out of hot water all the time, even with a 50 gal tank. One night when I ran out I had to go plug the exhaust fan in so the gas would kick on and I had a really good thought(at least I told my self this). I bought a cheap, $65.00 bell and gossett pump and added it into the line on my side arm exchanger. Too a few copper fittings, valves and about an hour to do after the heater was drained. I put the pump on a switch and if the little women were going to be doing laundry and such all day all they had to do was plug the pump in, otherwise it worked on convection like normal. Never ran out after that. Wish I had taken a picture now, we have since moved.

 

[farmkid2590]

Sorry to revive a semi-old thread but I am about to install a second water heater in an addition. I have a side arm unit on the first water heater and it works ok. I am leaning towards a plate heat exchanger on the second water heater. My only concern is expansion. Probably not something to worry about as I am on well water and have a small expansion tank but it is about 70' from where the second water heater is. I can only assume any pressure even that far away will push back to that expansion tank. I would have never thought about it but I read where a few guys had pressure problems (blow ups!) when they didn't use an expansion tank, can only assume they were on city water.... Do all of you guys who have a PHX have well water?

I plan on having the PHX ahead of the water heater to either totally heat my domestic water or at least pre heat it. Thanks for any info!

 

[lindnova]

I have never heard of anyone here having problems. It makes sense though that there is some expansion. There also could be contraction that could suck in the tank, but the water pressure would take care of that. I don't think it is significant enough to worry about.

I have a check valve between my pressure tank and water heater . I'm sure a small gradual movement would happen in the case of water heater expansion. No different if on city water or well expansion tank.

Heating with an exchanger is no different pressure wise than heating with propane or electric. If the tank did get over-pressured for some reason, the pressure-relief valve would relieve it.

Mythbusters took the pressure relieve valves off and made rockets!

 

[Landmark]

Never had any problem with mine. Water gets a tad hotter as well pump kicks pressure up somtimes. But thats two floors up from heater.

 

[Dustyw]

I actually forgot about this thread, but just a couple of months ago I finally finished installing a flat plate exchanger. No check valves or expansion tank, not sure if it's necessary or not but I've had no problems so far.

 

[Landmark]

View attachment 487758 I actually forgot about this thread, but just a couple of months ago I finally finished installing a flat plate exchanger. No check valves or expansion tank, not sure if it's necessary or not but I've had no problems so far.

Looks good. Nice job

 

[msmith]

If you have a well, your holding tank should act as an expansion tank, otherwise, I would highly recommend one.

 

[Landmark]

If you have a well, your holding tank should act as an expansion tank, otherwise, I would highly recommend one.

Nah. I dont use my water tank as holding tank. I just pump cold water through the plate and have a mixing valve to regulate temp. Works fine

 

[NSMaple1]

Nah. I dont use my water tank as holding tank. I just pump cold water through the plate and have a mixing valve to regulate temp. Works fine

Your pump must have a water ('cushion') tank attached to it?

What he meant was, the water/cushion (holding) tank acts as an expansion tank. Wasn't talking about a water heater tank.

Also don't think a person should have a check valve between the cushion tank & the water heater tank - that would prevent the cushion tank from serving as an expansion tank. A water heater tank could see a lot of expansion from full cold to full hot.

EDIT: Not sure all that was meant for the quoted post, I kinda talked across a couple things there...

 

[msmith]

This is a holding tank for a well...with an egg head shadow on it. It will act as an expansion tank. If you have public water, then you SHOULD have a check valve on your system where it comes in your house. In this case, you really need an expansion tank.

 

[Patvetzal]

This is a holding tank for a well...with an egg head shadow on it. It will act as an expansion tank. If you have public water, then you SHOULD have a check valve on your system where it comes in your house. In this case, you really need an expansion tank.


When I was servicing commercial heaters we would often pull the check valve flapper and drill a 1/8" hole in it to prevent the pressure relief valve from weeping. If you are slowly using water you might not notice but going from a cold tank to fully hot does give you a lot of expansion. This will not be noticed if someone opens a hot water tap or your tap drips....

 

[Landmark]

Your pump must have a water ('cushion') tank attached to it?

What he meant was, the water/cushion (holding) tank acts as an expansion tank. Wasn't talking about a water heater tank.

Also don't think a person should have a check valve between the cushion tank & the water heater tank - that would prevent the cushion tank from serving as an expansion tank. A water heater tank could see a lot of expansion from full cold to full hot.

EDIT: Not sure all that was meant for the quoted post, I kinda talked across a couple things there...

Water is in tank if thats what yall where getting at. Hear plate above it but i do not use my water tank to hold the hot water from plate. Man this seems complicated with all this talk. Just glad i can hook mine up and make it work.