HELP with current hot water heat

[skindaddy]

i have a 30 plate heat exhanger just turned water on to it. When you take a shower its hot at first then slowly gets colder until its just luke warm at end of shower.

it does not automatic siphon into water heater. and dont really want to put a pump on it.

what do you guys think about my problem and setup?

it also seems to slow flow down a bit running through the exchanger which is probably normal.

 

[showrguy]

how long has it been installed ?
did it work good before ?
those plate exchangers work really well, but they do get clogged up with water/mineral deposits and need to be cleaned/flushed periodicly..

dunno if that helps ??

 

[wrightk20]

it appears that it is hooked up like a sidearm should be. I can't tell from the pics. Does your water supply run through the 30 plate? If it is hooked up like a sidearm then i would think that would be your problem. Make sure your hot supply off of the water heater run to 30 plate and then to supply your house. Then just turn off the water heater. Kevin

 

[deutzman]

I don't use a tank so I'll just take a guess from what I see in the pictures. "If" your hot water from the plate exchanger is going in the lower end of the hot water tank then it looks like your cold water is tee'd in to the top of the tank on the left side and runs cold over to the exchanger. Looks to me like you'd need a ball valve below that tee to the tank and keep it closed off while heating with the plate exchanger. Again I don't use a tank and get hot water straight through the exchanger so I could be way off on what I think.

If all this is reversed then I have no idea at all. I'm sure I'm about to learn something. Old as I am that means I'll forget something too. :yoyo:

 

[wrightk20]

I think how you have it hooked up you wanted it to thermosiphon to heat the water in the tank but i don't think that would work very well with a plate exchanger without having a pump to circulate the dhw inside the tank. A ball valve below the top tee would allow it to work but it would not heat the water in the tank. It would just pull cold water from the bottom of the tank. The plate exchanger is most of the time used as a hot water on demand system. You could have it where it would put hot water into the tank when you were using hot water but if it sits for awhile you would slowly lose the heat that you put into the tank. The way it is hooked up now if you put that valve under the tee then you would have the hot water on demand type of system.

 

[skindaddy]

it was put in last fall its a new house we had water in it, to test for leaks drained it. and have not used it till this year.

the cold side is not touched at all

the cold comes from bottom of tank into exchanger out of exchanger and over to tee to supply house.

do you think cold water is coming out of the tank where the tee is and mixing with the water from the exchanger, is that why you say to put valve under tee?

 

[Deereman76]

I will take a shot........

For this to work, there has to be more lift on the heat exchanger side of the circuit, to force the warm water down into the water heater tank. With the top of your tank being nearly level with the heat exchanger, the "Lift" of the heat exchanger side is not enough to push the hot water down into the water heater on the right. The solution would be to lower the heat exchanger (or raise the water heater) to get the thermosiphon going...


To Add:
Masonry Stove Builders - Domestic Hot Water

From the above link:
Best efficiency is obtained when horizontal distance to the tank is 4 ft. (1.2 m) or less and the vertical distance is 6 feet (1.8m) or more.

Obviously you do not need "Best efficiency" but what you have now is obviously not working...

Edit to add, that link is really good reading for anybody wanting to set up a DHW adder...

 

[wrightk20]

By installing a valve in there with it closed it will pull water through the exchanger and into your house. Right now with it hooked up in parallel with the tank when you want hot water in the house it will pull most of the water from the tank and very little through the exchanger. You want full flow through the exchanger to get hot enough water. If you had a sidearm exchanger in the location of the plate exchanger then it would thermosiphon and heat the water in the tank, but with the plate exchanger you will have to bypass the tank and just run the water through the plate exchanger. Kevin

 

[Deereman76]

Ah yes, never thought about useing the heat exchanger for an On Demand type setup..... A valve would be necessary between the tee on top and the tank..You would have to turn it back on if you choose to use gas to make hot water....

 

[wrightk20]

Yep. The way the piping is now that would be the simplest way to go. Otherwise it would be alot of change in the plumbing already there. Just make sure to turn the power or gas off to the hotwater heater so that it doesn't kick in and as long as you have the wood boiler water temp high enough you should have hot water as much as you want. I don't have mine set up that way. i heard the bad things about how they can plug up over time and limit flow so i installed a sidearm on my hot water tank and it just keeps the water in the tank at my boiler water temp. Its about 185 degrees so i installed a anti-scald valve on it to cool the output down to roughly 140F. Kevin

 

[skindaddy]

appreciate the ideas guys, i will put a valve in there and see. i have had the gas off for 2 days now just need to get out the kinks for hotter, and more water.

do you heat exchangers slow your flow down at all, seems mine did a bit, have to figure out how to clean although it should be

i dont really need the thermosiphon but if it was close to doing it i would have.

i thought it would be instant heat like you talk about , because i have another 30 plate after this that heats the radiant tubes for the floor heat and when i was fillling that it was hot as you want much as you want. here's a pic on the other wall thought i would share just cause i had it on my computer.

 

[skindaddy]

you posted while i was typing, i did not know when i bought that they can plug up!

do you know what model temper valve you have? i see most of them say to mount it below the tank for life expectancy. well that's alot of ugly plumbing to get my cold and hot down below for that

 

[skindaddy]

soory about all the threads
what happens when the water just sits in the plate exhanger when no hot water is being drawn?

when we tested last year the hot pipes got so hot the faucet was actually hot to touch at the other end of house.

trapped water in a 180* exchanger scares me a little like a bomb thats why i put in the air bleeder.

 

[wrightk20]

the valve i have is a Watts brand from menards. 3/4 inch sweat on. model # Lf1170-ut-m2. The water in the exchanger just sits there when not in use. No need to worry about pressure building because the relief valvie on the hot water tank will still work if there was an over pressure situation but it won't be caused by the exchanger. Kevin

 

[wrightk20]

my valve is installed right above my tank and its been there 3 years and has worked good so far. The installer installed it that way so i figured it was right but reading the paper that i got with the valve it does say to have it 8" to 12" below the hot water supply feed. Kevin

 

[12vdzl]

I would like to suggest checking flow if you're going to install a ballvalve on the W/H. Boiler and cold water flow should be opposite of each other. In other words, hot flows down into the exchanger while cold water would flow up through the exchanger.

 

[skindaddy]

that is good by chance that is how we have it, but i dont think it was planned that way.

wood boiler side comes in on top out on bottom, hot water side cold comes in bottom and out top and over to top of water heater.

 

[wrightk20]

Hey i was wondering if you have made any progress with the hot water yet? Kevin

 

[Patrick62]

thermosiphon 101

I am running one out here, a little different setup, but darned effective.

Heater is a older cookstove with a water jacket in firebox. An incredible amount of heat available :msp_w00t:

there was concern that I figured out in installing about cold water bypassing the water heater tank and simply flowing thru the jacket. Simple solution was to plumb the jacket to the tank with separate pipes from the in/out to the rest of the house. This way the water heats up, and circulates all on it's own. When fire is out it wants to circulate in reverse. Keeping stove warm. We plumbed in a one way check valve on the top side. Works okay that way, takes a few more minutes for the water to force the valve open.

T/P valve on tank had to be modified. The over temperature part was removed as I am capable of heating water way past anything considered "safe". actually "dangerous" is about accurate :angry2:

 

[skindaddy]

hey kevin, and others who helped
thank you, worked on it sunday, the ball valve on top was the way to go that cured it for sure, also i went ahead and put that temper valve in why i was cutting it apart,took awhile to mount it up and keep it clean as i could. those things are a pain to keep plumbing looking good with 3 ports, but i built it so it only uses the temper valve with wood burner, not when using propane, i figured propane is a little different and wasn't sure if i would like the temper valve, but now its in place and glad it is.

unlimited hot water NOW with wood.

thanks again fellas works beautiful