Print

[clydem]

I have a side arm heat exchanger on my 55gal water heater, it is the first device off the boiler.

 When we take a shower the first 3 to 5 min the water is the preferred temperature (mixing valve set to 120) after that the temp drops but is still comfortable but noticeably lower. It seems like the water in the top of the tank is hot but after a few min the water drawn off a lower portion of the tank is a lower temp. 

I have been wondering if a plate heat exchanger would work better or should I put a circulating pump in to transfer more heat evenly to the tank.  I would prefer the passive method rather than a pump that would consume electricity. 

Someone suggested that a pump with a pressure switch that starts the pump on a pressure drop would cause the pump to only run when hot water is needed. 

What is the opinions of the list?

thanks
Clyde

[RSI]

If you put in a pump you would want to make it run on a thermostat not a pressure switch.
What kind of sidearm do you have? If it just has a single 3/4" pipe through the center you don't get very good heat transfer.

With a plate heat exchanger if you go a long time between running any hot water the tank cools a little and the water heater might need to run a little.

So in my opinion, side arms are better for low usage and plates are better for medium to high DHW usage.

[clydem]

If you put in a pump you would want to make it run on a thermostat not a pressure switch.
What kind of sidearm do you have? If it just has a single 3/4" pipe through the center you don't get very good heat transfer.

The side arm exchanger I have is about 40 inches long and is a 3/4 copper inside a 1-1/4 copper tube I don't think it has enough surface area to be efficient.  I.m just looking for a better more efficient way to heat the water more evenly. I need to keep the wife happy on her long showers.  It's hell when they have you on the incentive plan!If mommy is not happy no one's happy....Thanks for your time and advice.Clyde

With a plate heat exchanger if you go a long time between running any hot water the tank cools a little and the water heater might need to run a little.

So in my opinion, side arms are better for low usage and plates are better for medium to high DHW usage.
[/color]

[RSI]

If you don't use a lot of water at one time then a pump should be all you need. From what I have seen it takes a good 3+ hours to heat a tank from 50 degree water with that type side arm and a pump.You get the whole tank heated pumping it so it is a lot more capacity.

If you don't run out of hot water when the boiler is shut down and the water heater is running then a pump should make it keep up.

[tulenutn2o]

If no children in the house, set the mix valve so it is not doing anything. My set-up is with a 40gal tank and I can take a shower til I turn into a prune with no change. My pump off boiler runs 24/7 at 170deg. . First thru side-arm, heat exchanger, back to boiler.

[Trint]

Outside question but is your water heater clean, is the drip tube still there, and whats your boiler temp?  I have the same set up as you on the water heater and can have 5 people take a shower with no drawdown, my boiler is set at 180 how ever.  The reason I ask the other questions is that my drip tube was orginally broke (dumping cold water at top of tank opposed to the bottom) and I had to clean about an inch of settiment out of the tank to let water flow well.

[plumb bob]

I agree with Trint. Depending on the age of the heater your dip tube may be disintegrated or gone all together, thus your only using water off the top 1/3 (maybe) of your water heater. Pull the cold supply out of the water heater and look to see if the white flanged plastic dip tube is intact.It should extend at least two thirds of the way down.

P.S.  I am running a 5036 installed in 2011 with sidearm, 50 gal. virtually unlimited hw, set points at 185-175.