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[trz]

Explain how they work.    It seem to me water from the boiler enters the house runs thru one side of the plate exchanger and on to whereever it goes from there.   In the mean time domestic hot water runs from the house water inlet thru the other side of the exchanger and into the existing water heater.   Then that water sits in the water heater until you turn the hot water tap on and the water you first get thru the tap is the water that's been sitting for how ever long in the water heater.   So, the domestic water you get  from heating it with the boiler is not consistent in temp. it all depends on how long it's been sitting in the water heater.    The longer it sits without being used the less hot it is.  As you draw water from the water heater more water passes thru the exchanger, heats up as it passes thru and enters the water heater.     

   This doesn't seem llike it's right to me so please explain to me how it works if this is wrong.                                                                                                                          thanks

[Scott7m]

Plate exchangers are very consistent, a water heater loses very little.  As long as someone takes a shower once per day you'll never notice a difference in water temps.

Furnace water flows through half of the plates, your supply line going into your tank goes into the other side so the water is pre heated, and goes into your tank well over the tanks set point so that it will never have to kick on.

The only time a plate would be bad is if it were in a situation where you only used water once every few days. 

[RSI]

You are right that the temperature coming out of the plate is very inconsistent but the tank acts as a buffer. The water entering the tank is enough hotter that it makes up for the heat lost from sitting.

It works very well with normal usage. If it is for somewhere with little or no use for several days a sidearm would be a better choice.

[trz]

So, can you think of any concievable reason why, with this setup, my domestic water would be 30-40 degrees colder on some days than it is on other days.    It's not very often, maybe a few times thru the heating season that my water does that. I'll go to use the hot water and it's only 'warm' it might stay like that for a couple days anfg then it's hot again.   Very aggrevating

[Scott7m]

So, can you think of any concievable reason why, with this setup, my domestic water would be 30-40 degrees colder on some days than it is on other days.    It's not very often, maybe a few times thru the heating season that my water does that. I'll go to use the hot water and it's only 'warm' it might stay like that for a couple days anfg then it's hot again.   Very aggrevating

You mean it's like your using water daily and then suddenly, "bam" you don't have any?

Is it in the supply going into the tank?

Does it ever coincide with your fire going out or anything?

[trz]

yep  'bam' i only have 'warm' and then maybe a day or two later 'bam' it will  be good and hot again.,    doesnt' have anything to do with the fire in the box cuz that never goes out or dies down .

[Scott7m]

yep  'bam' i only have 'warm' and then maybe a day or two later 'bam' it will  be good and hot again.,    doesnt' have anything to do with the fire in the box cuz that never goes out or dies down .

I'd like to see some pics of how it was plumbed in, any chance of that?

[trz]

I might be able to get a pic but i don't know if you would be able to make heads or tails of it.    When i look at it I get a headache.   lol.      I had a professional installer do it and while we were doing it , it made sense to me but now when i look at it I get frustrated cuz i cnat figure it out.     I'll see if i can get a pic in the next couple days.

[Scott7m]

I usually get a good chuckle when I see how people install some of these things on here...  I often see enough valves and fittings to do 4 installs on only one

 I have no idea why people want to make something so simple, so complicated

post a pic if you can

[oldchenowth]

I'll bet trz had the same plumber that built my house in the early 1900's. the only thing that is straight forward in my house is the owb  plumbing. 
It really is easy.  If I can do it, anyone can.  Domestic into the hx, out to the water heater opposite flow of the owb.  Even with a 10 plate, I had unlimited consistent hot water.  All held in the tank.  Should not give you a headache at all to decifer it.

[fireboss]

I have a 40 plate ex  and iam heating 3,000sqr house and hot water and we can take showers all day long and never run out of hot water or heat!

[loneryder]

I only get my HW from the plate exchanger and temps are consistent as any hot water heater.