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[Axeman]

We heat our home with a central boiler outdoor stove. Currently we heat our water with an electric water heater. I am looking at getting a plate heat exchanger to heat our domestic water but i have no idea what size i would need.

Any help on this subject is appreciated!

[CountryBoyJohn]

A 20 plate should be sufficient. I think most are around 3.5" x 8"-10". I filled a 400 gallon hot tub and never ran out. I'm plumbed before my tank and the tank is off at the breaker.

[Axeman]

So the plate heat exchangers do not have to be hooked directly into the water heater?

[Wood Nutt]

No, no direct tank connection is required.  I have a 30 plate just to be sure and an electiric demand water heater.  I shut off all of the circuits on the electric demand heater so it is nothing more than a pipe in the winter and I have never ran out of hot water. 

Over the holidays we had 9 people staying in the house and the shower ran for probably 1.5 hours+ straight a couple mornings.  if that did not run the plate exchanger at max, not sure what would.

You also need to add a tempering valve after the plate exchanger on the potable water side of to avoid scald potentials at your appliances (sinks, showers, etc).  there are plenty of examples on here if you look around a little on various ways to set this up.

[RSI]

You will want to get a 5x12" or 5x13" plate.
20 plate will work fine unless you are very near the limits on boiler water flow. If you are, going with a 30 plate will usually work without needing to get a larger pump.

[LittleJohn]

SIDEARM HEATERS, also work 

[Axeman]

Thanks for all the help! Much appreciated.

[kommandokenny]

http://outdoorwoodfurnaceinfo.com/forum/index.php?topic=6915.0

[5050racing]

My system is plumbed direct but it pass thru the domestic hot water heat changer from central boiler you will need a mixing valve also to cool water coming out of hot water heater

[LittleJohn]

My system is plumbed direct but it pass thru the domestic hot water heat changer from central boiler you will need a mixing valve also to cool water coming out of hot water heater

To clarify, you have to put a mix/tempering valve on the Domestic hot water line coming out of water heater, other-wise you get 180f to faucet (OUCH).  By the way, you can run un-tempered water to applicances such as Dishwasher and clothes washer, IF DESIRED

[kommandokenny]

Yep,, and if you use a small ten plate xch., you won't need a mixing valve, as your water won't get hot.

[RSI]

Yep,, and if you use a small ten plate xch., you won't need a mixing valve, as your water won't get hot.

A small 10 plate could. Just not how yours was plumbed. A large plate probably wouldn't have done much better in the same place.

[kommandokenny]

Yep your right about that ..
but,,, does anyone on the forum use a small 10 plate by itself, in any configuration.??

[fireboss]

I heat my pool with a ten plate,  I would use one to heat my hot water, I had my pool up to 95 when I forgot I was heating the pool

[kommandokenny]

not without a circulating pump .......[on the domestic ] pool side]