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[easyrider470]

I have a sidearm that will not support the usage of hot water in my new house.
What I want to do is replace the sidearm with a 40 plate heat exchanger.  House is brand spanking new with a very nice manifold and taco computer to run all my zones.  I would like to remove the sidearm and install a plate exchanger but I am a little worried about my circulating pump.  Normally they go into the bottom of the HWH but the plumber decided to do it the other way simply because of the sidearm.  Well, since I'm ditching the sidearm I should be ok to go back to the re-circ pump in the standard configuration right?

I will post a picture if I can later this evening so you can see exactly what I would like to do.

[slimjim]

I would like to see a picture of how it's done now and I would bet we can fix it!

[CountryBoyJohn]

You don't need a circ pump and you only need a 20 plate, not a 40. Plumb your cold supply into one side and out the other side right into the cold supply port in your tank. The water gets heated before it dumps into your tank. I'm plumbed his way and I filled my hot tub with 400 gallons of 110° water. UNLIMITED!

[easyrider470]

Thanks slimjim and CountryBoyJohn for the replies i'll get the pics tonight

CoutryBoyJohn:  My home is pretty big and the re-circ pump greatly imporves the time it takes to get the hot water to the furthest location when it's called for.  Sticking with that for sure.  However, I will also say that I have 4 kids and a wife that loves to take baths!  We need to have hot water in large quantities almost every day.  Between laundry and dishwasher and baths/showers there isn't a time when the hot water is utilized.  I had a 40 plate at my other house and 2 50 gallon hot water heaters that were reseviours....never ever ran out of water.  Now is that the only way to do it...NO but it was the only way in that house with the way it was already set up.

I'll need to do a little more research but the way I am set up now, the plate exchanger will only get water sent to it when there is a call for hot water.  My manifold system will open an electric valve and send the water to the plate exahanger (kind of like tankless) to replenish anything we have used.  I wonder if this is the best way to do it only because that means I will be maintaining the temp in the HWH with electric.  I was wondering if the sidearm could still be utilized to maintain a set temp in the HWH but the plate exchanger could be used in line in front of the sidearm for those times where the sidearm can not keep up.  Does that make sense?

[CountryBoyJohn]

Yes, you can use both. Yoderheating advocates for this setup often.

As far as your pump goes, I must not understnd how you are using it.   Pictures will help.

[easyrider470]

I'll try to get some tonight.

Pump is used to keep constant pressure in the line so when you hit the faucet for hot...it's there in 2 seconds.  My other house did not have this and it would take F...OR...E...VER to get hot water upstairs. 

I told myself when we built the new house this would not be an issue for us.

[cando attitude]

Hi Easy,

Having just installed a plate exchanger for my DHW, last weekend, I was very recently in your shoes.  At first I was doing some soul-searching (as well as OWFI.com searching) and finally came to the conclusion that I wanted to install a plate style heat exchanger.  My next dilemma was size (20 or 30 plate). 

After reading all the posts I could on this site, and hearing guys state things like " a 20 plate will make all the hot water you want",  I decided to take a stab at a 20 plate (make sure it's a 5"x12".  Let me say that those guys were right and a 20 plate will do all that I want and then some.  I have mine set up such that the exchanger is located before the tank for buffering reasons.  Note that I do not have a mixing valve.  I control the water temperature coming off the exchanger by controlling the flow of water going to the exchanger on the boiler side.

With a plate exchanger, the potable water side only goes through the exchanger one time and the temperature you get on the exit side is what you get.  I guess you could hook one up with a pump and have it act like a side arm.  With a sidearm, the potable water either by convection or forced via pump, goes through the exchanger many times.  It needs to do this due to the fact that the heat transfer rate is not as significant as a plate setup.  This is the reason why sidearm (non pump setups) need a "recovery" period and are more prone to temperature fluctuations.

Anyway, I've rambled on enough.

Hope this helps,

Cando

[easyrider470]

Thanks CAN DO.  That is helpful info.

I am still trying to get pics taken and posted...might have enough time this weekend.

I am going to be using the plate exchanger in an ON DEMAND type situation....meaning that it will be plumbed in but only have potable water and boiler water running through it when there is a call for hot water.  At least that's what I am thinking.  Not sure if I can even do it that way and keep the hot water heater up to temp for a continuous flow of hot water.

I have an aquastat on the outlet side of the hot water heater to prevent anything to hot from running through the pipes.  I'm not sure this is the best way with a plate exchanger and am open to suggestions.

[cando attitude]

You can absolutely use it for an on-demand setup.  I essentially have mine setup as such only the exchanger is located prior to the tank, so that it dumps hot water into the tank and I have killed the breaker for my hot water heater.  My tank now is just a storage tank.  With this setup, the exchanger puts out water in the 130-140F range and will continue to do so as long as there's wood in the stove.

If you have it located after the tank then you really need to ensure you have some sort of tempering valve as you will see much more significant temperature variation.  This is due to the fact that the temperature exiting the exchanger on the potable side is proportional to the flow rate of that water going through the exchanger.  Thus when you're in the bathroom perhaps shaving with the hot water on running slow, this water has a much longer residence time in the exchanger and will be much hotter than when water is full on say when you're filling a bath tub.

I can snap a picture of my setup if you like.

Cando

[Chicken farmer]

This is not a hijacking........

Cando - I see you are in central OH, where at, if I may ask? I'm close to Lima.

[RSI]

I have an aquastat on the outlet side of the hot water heater to prevent anything to hot from running through the pipes.  I'm not sure this is the best way with a plate exchanger and am open to suggestions.

What does the aquastat control? That sounds like it could be the reason for not enough hot water. If you are using a sidearm and only heating the tank to usable temp, you will run out very quick. You need to use a mixing valve and let the water get much hotter in the tank. If you are pumping the DHW through the sidearm then it might work keeping the water in the tank at useable temperature but will still be not great.

[cando attitude]

This is not a hijacking........

Cando - I see you are in central OH, where at, if I may ask? I'm close to Lima.

Morning Chicken Farmer,

Perhaps southern Ohio is more representative.  I live south of Columbus down around Chillicothe.  I typically head your way a few times during the winter, on my way to the upper, lower point of Michigan to do a little sleddin (Ski-doo style)

Cando

[Chicken farmer]

I've got some buddies that hit Gaylord for a few days and then head up to Munising for a few days. They go in January usually.