Outdoor Wood Furnace Info
All-Purpose OWF Discussions => Plumbing => Topic started by: SperleFarms on January 20, 2013, 07:13:51 PM
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Looking for some advice on domestic hot water temperature….
My OWB water temperature set point is 190°. I have less than a 1° temperature drop over approximately 175’ run of ThermoPEX. I haven’t measured the water temperature out of the T&P valve on my hot water heater, but it’s very hot. Needless to say the plate heat exchanger is doing it's job! My problem is the water temperature at the faucet, all of them. Again I haven’t measured this temperature, but I would describe it as a little better than luke warm. In my opinion the only thing standing between me and nice hot water is the Honeywell AMX Series mixing valve. The valve was installed per the manufacturer’s instructions, and I’ve even pulled it a few times thinking it was dirty or clogged with some debris. Does anyone have any advice, or experienced something similar?
I’ve attached a few images for reference.
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I could be wrong, but I do not believe you can use a plate exchanger in that configuration.
You have it plumbed like a sidearm. Sidearms use gravity flow, plate exchangers use actual flow.
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Yeah, I don't think they work very good that way.
Have you held your hand on the pipe coming out of the tank into the mixing valve? If the plate is working at all there you shouldn't be able to keep your hand on that pipe for more that a second with a faucet running.
If that is the problem the best / cheapest fix would be to put a small pump right above the plate.
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I have the same set up on my electric water heater with a plate and it work great. I go into the anode rod port on top rather than teeing into the pop off port. Are you sure you are not air locked on your domestic side? You might try bleeding more air off that bleeder elbow I see in your picture. I've heard of some gas water heaters that just won't thermocirculate and a pump like a bronze 006 taco put on the domestic side will circ the water and it works.
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Well, that is why I said to see how hot the outlet pipe is.
has it ever worked? If it did and you have hard water the plate is most likely plugged. I have seen sidearms with a straight through 3/4" pipe plug up solid.
If it isn't plugged and the water coming out of the tank isn't hot then a pump right above the plate will fix it and give way more hot water than without can make.
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Why would you want to use another pump? Just something else using 5 bucks a month of electric, looks to me like a sidearm should have just been used to start with, I don't see the benefit of that plate installed that way vs a side arm
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If you put the pump on a thermostat it will use less than a dollar a month.
Cheapest way to get it working right.
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Yea if it was on a stat, but what were the benefits of doing it that way vs a side arm?
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Not having to buy a sidearm and more hot water capacity
The water is only hot at the top of the tank with a sidearm unless there is a pump on it. With a pump the whole tank gets hot.
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So you think a 10 plate installed the way it is there is better than a sidearm?
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With a pump it is. Without probably not. With a pump it will give way faster heat recovery.
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Yea I agree with a pump, but not the way it was.. A pump is the cheapest way to fix it now, but initially I would think a side arm woulda done well
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Yeah I agree on that.
Too many bends to get good natural flow on that setup.
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Yea... That was my thoughts
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Let me clarify a few things….
First, the plate was used due to the extremely close proximity of the hot water heater and the gas furnace. In order to use a sidearm I would have needed to move the hot water heater, thus re-plumbing and re-ventilating the unit. I didn’t want to open a can of worm so to speak, so we used a plate.
Second, the plate seems to be working extremely well. The piping between the plate and the T&P valve is EXTREMLY hot, as is the nipple coming out of the top of the hot water heater below the mixing valve. Touch these for more than half a second and they’ll blister you hand, believe me I know. :'(
Third, I’ve drained several five gallon buckets of water from both the T&P valve and the drain at the bottom of the tank. The water is scalding hot, bucket after bucket after bucket.
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Sounds like you have a bad mixing valve then... Seems you have hot water everywhere besides where you need it
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He said he drained 3 5 gallon buckets out of the tank and it was scalding.....
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Thanks for the help guys, I'll post an update when I figure this thing out.
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If the water in the tank is hot then it is the mixing valve.
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mostly i think as rsi it is the mixing valve but i have some things i am uncertain of..couple of thoughts what do you guys think?
the cold water supply is likley on a dip tube about 2/3 of the way down the tank.
the way the thing is set up to siphon i have a feeling it may only create hot water to the level of entry as there is no reason for the siphon effect to continue?
if there happens to be even a short dip tube on the hot side it may be just at the level where the water is luke warm?
i would either take the mixing valve out and try it that way and if this still does not work...eliminate the whole siphon effect and make it with a couple of valves to either feed the tankk from the top (as designed) in summer and close a valve and open a valve and feed the cold supply into the plate exchanger and forget about having the tank as reserve.
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I think you may have already mentioned this but I don't want to read over the whole thread again right now.
Was it working ok with the gas heater running? If it was then it probably isn't the mixing valve and it the problem was there then it is the mixing valve.
I have never seen a dip tube on the hot side of a water heater. If someone put it in the wrong with it will not work right.
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New valve installed, we’ve got hot water coming out our ears. Problem solved, for now anyway! :thumbup:
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Sounds good! I was gonna be shocked if that wasnt the problem
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I amno expert like most of these other guys, so I will teel you the way I did mine w/o a circ pump. I disconnected mine before the cold inlet side of the water heater and forced it to the plate first, back to the inlet side of the heater. Mine is AFTER the forced air HX to make hot water with no (I know "stupid". I take full responsibility) mixing valve. Turned the breaker off and have unlimited hot water. Just my $0.02
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if you want true control of your water heater with a OWB it needs a stat.....i use a plate heat exchanger,007 bronze pump,aqua-stat and a zone valve.....you pull water from the bottom of the tank threw the plate and in to where the TRV goes.........there is a well in the tee setup in the drain port to where your aqua-stat probe goes and when you set the stat for 120 you get 120 no guess work..........side arms should not be aloud to be sold!!! ......worked on and replaced tons of mixing valves in schools and other places(pipefitter for 20+ years) as when they fail you get burned!!!....so when i started sellin' OWB i came up with a better and no way to get burned......here is a pic of mine...hard to see all of it....
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That works fine, but lord help the person if they ever need to replace that hot water tank..
I install 20 plates with 1" ports and use various pumps depending on the job, I've never had an issue of water being to hot or to cold, everyone seems to love it. Also I've never noticed my cold handle on the shower needing to be in different positions, so it's pretty consistent
I agree about mixing valves, don't like them
I just like to keep things as simple as possible...
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Scott, I agree with you. I recently found myself in the position of "what to do?" I really like the way ghitch set his up and I had been thinking that I would do about the same, usuing a pump and aquastat for the most consistent temp. The almight dollar won the fight and I ended up just plumbing it in to the incoming line, figuring I'd be keeping a close eye on it for a while. So far I can't be happier. I'm still a little uneasy about the high water temp flowing into the water tank. I installed an in-line thermometer. It does depend on water volume being drawn. For example at prolonged light volume usage the water temp flowing into the tank is around 160 to 170 and that would increase the tank temp. I do notice my water temp rise while in the shower and I have to adjust the cold. I'm used to this as it always happened mid-shower with oil burner as that always kicked on while showering (I could hear it) (oh, by the way, it's great NOT to hear it anymore :thumbup:). When I fill my washing machine which is located right next to the water heater, the temp flowing through the HX drops to around 140+ which is still higher than what my original heater set point is. Boiler runs 185-190 with 009 pump pushing about 125' one way to 10 plate HX and then forced air HX. I have no complaints with this setup. 009 may not be real fast, but it is a workhorse and has been for 5 seasons now.
ghitch - If I were to install as you did, where do you position the temp probe from the aquastat?? That was my biggest question. My local true value plumbing guy (who I'd trust with just about anything) suggested cutting through the outer shell and using a strap-on type aquastat to try to get the truest tank reading. I figure if the probe is located somewhere in-line then the line would cool more quickly causing the pump to short-cycle often. Just my thought on it. I'm curious.
Jeff
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Yea if you let it trickle it could get hotter, but under normal use, I love it
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i took a pic of the tee setup......i took a 3/4" brass plug and drilled a 3/8" OD hole in it and silver solder a 12" 3/8" copper pipe to the brass plug and sealed the end......as in the pic you can see the probe from the aqua stat in it......it will sense the water temp when the pump pulls the hot water to the bottom of the tank and push's the cold the threw the HX and dumps the hot in the top of the tank.....
btw....this is in the 10th year runnin' with no parts replaced(knock on wood!!!!)
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ghitch - That is a pretty ingenious idea. If I read it correctly you have a 3/8 x 12" copper pipe slid into the 3/4" so that the probe is actually within the tank? That's a cool idea. Setup basically how the aquastat on my Wood Doctor boiler is set up. Has a tube welded through the wall that the probe sits within. Better and cheaper than the idea I had using the strap-on aquastat. I just bought one of those Johnson A419 aquastats so I know it would be cheaper than the strap-on one my true value guy has to offer. That was about $130. He just got me the A419 for his cost of $82 with UPS charge.
Thanks for the pics and idea!!!
Jeff
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yep it's in the tank threw the tee.......your welcome....if you need any other help settin' it up just holler.....
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could i get a diagram of your set up? I think i would like to try it.