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[Firechaser]

Looking for a little advice on my install. I am putting in a plate exchanger to heat my water. It has 1" outlets. This works well for my 1" lines from the stove. My domestic lines are 3/4" to the water softener. Coming out of the softener they reduce to 1/2" and go into the hot water tank. I plan on putting the plate exchanger after the hot water tank and just turning power to the tank off in the winter. My question is what size lines do I need to go into my plate exchanger. Should I run 3/4" lines to my tank and then to the exchanger and then reduce them to 1/2" after. Or will 1/2" lines be sufficient? Thanks Tony

[RSI]

That is kind of odd. Normally they have 3/4" to the tank. Is the pipe coming out of the tank 1/2"
I see no point in going larger than 1/2" if that is what it is feeding. (unless it is a long run)

[Firechaser]

It's not a long run and the line coming out of the tank is 1/2".

[Ridgekid]

I would make a modifcation then. I would want to use the HWH as a storage tank and heat the water before it goes into the HWH.

Something else to rememeber- That water is going to be scalding hot. Adding to the HWH first allows it to act like a mixing valve allowing it to cool a little before use.

 

[mikenc]

If you are not having any flow problems in faucets leave 1/2 inch. most hot water tanks are feed with 3/4 in 3/4 out to house. If you are having problems with flow I would change to 3/4. If you have noticed when you are taking a shower and some one turns on hot water in kitchen your shower changes temp I would change pipe size unless this is not a bother. Placing heat exchanger after water heater allows you to turn water heater off when using OWB. Before you will may need to keep power to water heater. Remember water out off heat exchanger will be close to boiler temp. May need to install tempering valve especially wtih small children.

[Firechaser]

I PLAN TO USE A TEMPERING VALVE AND I THINK I WILL CHANGE THE LINES WHILE I'M AT IT. THANKS

[RSI]

If you put the plate heat exchanger after the tank and the boiler goes out you won't have any hot water. Putting it before usually is better. If the heater runs it won't be much. You can always add a recirc pump to keep it from running.

[yoderheating]

Always place the heat exchanger before the HWH. If not you will get fluctuation in water temperature.  The water temp coming from the heat exchanger depends on two things, boiler temps and water flow. In other words if you have the heat exchanger in line after the HWH you run the risk of having the temps change if more than one faucet is on at a time. For example, lets say you are taking a shower and the dishwasher kicks on. Because there is higher water flow going through the heat exchanger the water temp drops a little. The water becomes a little cool for you and you add more hot. Now the dishwasher stops. Now the water is too hot so you adjust it cooler. Then your wife turns of the sink and your shower cools again. Get the picture? By placing the heat exchanger before the HWH you will allow the HWH to become a storage tank of consistent hot water. When the water from the heat exchanger fluctuates it then mixes with the 50 gal in the HWH and little fluctuations are never felt.

[muffin]

Always place the heat exchanger before the HWH. If not you will get fluctuation in water temperature.  The water temp coming from the heat exchanger depends on two things, boiler temps and water flow. In other words if you have the heat exchanger in line after the HWH you run the risk of having the temps change if more than one faucet is on at a time. For example, lets say you are taking a shower and the dishwasher kicks on. Because there is higher water flow going through the heat exchanger the water temp drops a little. The water becomes a little cool for you and you add more hot. Now the dishwasher stops. Now the water is too hot so you adjust it cooler. Then your wife turns of the sink and your shower cools again. Get the picture? By placing the heat exchanger before the HWH you will allow the HWH to become a storage tank of consistent hot water. When the water from the heat exchanger fluctuates it then mixes with the 50 gal in the HWH and little fluctuations are never felt.

Would the mixing value not help this as it would just add less cold water if the incomming water was not as hot?  Or are they not that sensitive.

[RSI]

Yes, the only thing the tank really does is give you storage.
Like said above, if you put it after and the boiler goes out (especially if you have a CB with the thermovalve) you won't have any hot water. If you put it before, you can leave the water heater turned on and it will not run as long as the OWB is heating it.

[yoderheating]

 My point is that if you install it before the HWH you will most likely never use a mixing valve, the HWH does the work for you. Adjust your furnace temp to what domestic water temps work well for you and you are good to go. I never have understood and benefit to installing the heat exchanger past the HWH. I have installed hundreds of furnaces for years and have never used mixing valves for domestic hot water and have never had any problems.

[muffin]

My point is that if you install it before the HWH you will most likely never use a mixing valve, the HWH does the work for you. Adjust your furnace temp to what domestic water temps work well for you and you are good to go. I never have understood and benefit to installing the heat exchanger past the HWH. I have installed hundreds of furnaces for years and have never used mixing valves for domestic hot water and have never had any problems.

This would provide more steady heat, but would also require the electric to kick on from time to time to maintain the heat.  I do not know how often or long that would cycle so I do not know how expensive it would be.  Perhaps it is negligible.  Anyone know what the maintainance heating is on a normal hot water tank?  Just curiose.  I think I pay about 6-8 cents a KW-hour.  Seems like only about 40cents an hour to run it then assuming it consumes about 5KW, probably only an hour a day, but thats still $12 a month.

[yoderheating]

 No, I turn off the breaker and have never had an issue with water cooling. There is only my wife and I in our home and we both work so we only use hot water in the mornings or evening and I have never had an issue with it. I guess if you went more than a day without using hot water there may be an issue but who does that? I have installed hundreds of furnaces like this and have never had anyone who had a problem with water cooling off.