Shaver - DHW with elec WH problems

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headleyj

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Ok, I hooked up my DHW coil in the Shaver just like the attached Word file states...EXCEPT, I used a Ranco thermostat instead of a cheaper one.

Problem is sometimes we run out of HW VERY FAST. I'm talking 5 minutes! My guess is the circ pump is coming on while I'm in the shower and the cold water coming in to fill the WH has higher pressure and it exits the WH before circulating to be warmed up. Reason I guess this is when I'm showering I can tell a very slight pressure drop at times, then a few minutes later, water starts to run colder, colder, colder.

Has anyone ever run into this?? Any idea what I did wrong?

I do know our road water pressure is 110psi, then runs 1/4 mi through 2" PVC. We have very good water pressure.

FYI - I don't know anything about how WH's are plumbed internally.
 
Our water starts cooling off after a couple showers, I believe some of my problem is too small of a pump.


Anyway, I have heard of people plumbing the opposite way that what Shaver says.

Where you Tee off at the drain, make that the outgoing water and where you Tee off the pressure valve, make that the return.


I heard that helpsSomething about how the hot water tank is designed and taking water that is heated instaed of hot water cooled by refill water.


I have thought of switching myself but I am concerned about picking up sludged from the bottom of the hot water tank.

We have well water and get that rusty sludge in the bottom.
 
Our water starts cooling off after a couple showers, I believe some of my problem is too small of a pump.


Anyway, I have heard of people plumbing the opposite way that what Shaver says.

Where you Tee off at the drain, make that the outgoing water and where you Tee off the pressure valve, make that the return.


I heard that helpsSomething about how the hot water tank is designed and taking water that is heated instaed of hot water cooled by refill water.


I have thought of switching myself but I am concerned about picking up sludged from the bottom of the hot water tank.

We have well water and get that rusty sludge in the bottom.

the "sludge" at the bottom is the reason I plumbed it the way Shaver says. I just don't get it - one shower, 5 minutes in and it's cold....not always though. I just don't understand it. I've got a Taco 011 - runs a total of 220' through 1" pex + the DHW coil - should be plenty of pump.
 
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There were a couple times when it seemed like the water wasn't heating very fast. I went out and opened the refill valve and heard air bubbles inside the water jacket. Must have had air in there. It did seem to help a little.

My wife likes to fill the tub clear up. usually we have to wait about 45 minutes to get really hot water after that.

But it sounds like yours is cooling way faster.


I do think the flood of cold water coming in to refill the hotwater tank has to be part of the problem.

We also have an 80 gal. tank and notice cooler water after a bath tub full. Showers aren't as noticeable because of less water used.


It does seem to be weather related because in warmer weather, it isn't as noticable.
 
I was curious if he got this sorted out . I use a taco ooo11 too. total 374' with around 5' of lift . I run out only after a full bath and it recovers fast. Pump is at the top and returning water to bottom. Any chance there might still be air in the line ? The coil is completely in the water ? Let us know what you find .
 
well haven't found much out - was watching the kiddo all weekend while wifey was working. Yeah there might still be air in the line, I bled it pretty good to start with though, but I'll try it some more.

WH and pump is in the basement. Stove is ~ 110' away and 8' higher in elevation. I did have time to watch the pump kick on though took about 5 minutes to heat WH up 5 degrees...(50gal WH)

One thing I didn't mention - I don't have any check valves. So when I'm using HW upstairs, am I draining my recirc loop or is the incoming cold water from the road keeping it at bay? (ie: cold water from road is fairly high pressure)

I did change 1 thing. I lowered the temp of the stat on the WH that controls the pump a bit....did this to increase the temp delta b/t the WH and stove. Stove is at 145°....WH is at ~120°...see explaination below.

(one somewhat irrelevant fact - when my WH elements were set at 120°, the pump stat consistently read 103-104°.....so there's a large bias there)

I'll check for air tonight. Any thoughts on the check valves? I could increase stove temp, but kinda hate to - heats house great at 145°.
 
I was curious if he got this sorted out . I use a taco ooo11 too. total 374' with around 5' of lift . I run out only after a full bath and it recovers fast. Pump is at the top and returning water to bottom. Any chance there might still be air in the line ? The coil is completely in the water ? Let us know what you find .

same here. didn't think about the coil being completely in water. I had some boiling issues earlier in the year when it was warmer outside cause my door leaks, lets air in and more than smolders the fire.... so I "undid" my overflow mod. It's still that way now. Now that's it's single frikin digits I could "redo" the overflow mod and see if that helps.

The DHW coil cover plate is completely siliconed up and the roof it packed FULL of insulation - I'd hate to undo that to check the DWH coil depth to water level "ratio". IIRC the coil was set down in there pretty good.
 
Seems like your temps are set low. I'm running mine at 170 &135 and never run out of hot water with a 40 gal tank. Pump is taking water out at the top and returns to the bottom. Something else - I'm pretty sure the cold water inlet extends into the lower half of a hot water tank, while hot water exits at the top. If the inlet happened to be broken off inside the tank, water could loop in and right back out without being heated. Of course, if the tank was working ok before the wood burner hookup........
 
I am running @148 at the stove and making good heat . I could go lower. WH temp set at 130*.I dont have any check valves and haven't needed them yet. Cant hurt to install them though. I think you might want to try that overflow tube like you said . Maybe try to raise the water as far as you possibly can and see if it makes any difference.
 
Seems like your temps are set low. I'm running mine at 170 &135 and never run out of hot water with a 40 gal tank. Pump is taking water out at the top and returns to the bottom. Something else - I'm pretty sure the cold water inlet extends into the lower half of a hot water tank, while hot water exits at the top. If the inlet happened to be broken off inside the tank, water could loop in and right back out without being heated. Of course, if the tank was working ok before the wood burner hookup........


Correct. All HWH's have what is called a dip tube that comes out of the cold inlet, runs to about 4"-6" off of the bottom, and it can break off or come loose. Also, all newer HWH's have ball check valves at the inlet/outlet to prevent thermosiphoning. They must be removed if you are using a siphoning type HX.
 
Correct. All HWH's have what is called a dip tube that comes out of the cold inlet, runs to about 4"-6" off of the bottom, and it can break off or come loose. Also, all newer HWH's have ball check valves at the inlet/outlet to prevent thermosiphoning. They must be removed if you are using a siphoning type HX.

Our HWH is 2.5 years old....no idea if it has what you're talking about.

I understand the 4-6" off the bottom thing, but can you explain what you mean by... "Also, all newer HWH's have ball check valves at the inlet/outlet to prevent thermosiphoning"
- are these ball check valves integrated into the HWH internals?

"They must be removed if you are using a siphoning type HX"
- please excuse my ignorance, but what a "siphoning type HX"
- how do you remove the ball check valves?
 
Seems like your temps are set low. I'm running mine at 170 &135 and never run out of hot water with a 40 gal tank. Pump is taking water out at the top and returns to the bottom. Something else - I'm pretty sure the cold water inlet extends into the lower half of a hot water tank, while hot water exits at the top. If the inlet happened to be broken off inside the tank, water could loop in and right back out without being heated. Of course, if the tank was working ok before the wood burner hookup........

HWH was working great before so I think it's something in the way I have it set-up.
 
Our HWH is 2.5 years old....no idea if it has what you're talking about.

I understand the 4-6" off the bottom thing, but can you explain what you mean by... "Also, all newer HWH's have ball check valves at the inlet/outlet to prevent thermosiphoning"
- are these ball check valves integrated into the HWH internals?

"They must be removed if you are using a siphoning type HX"
- please excuse my ignorance, but what a "siphoning type HX"
- how do you remove the ball check valves?


1. Hot water heaters have check valves inserted into the inlet/outlet fittings, to prevent siphoning (by temperature) or ghost flow of hot water back into the cold water line. difference in temp. between colder/hotter water causes the flow. As far as removal is concerned, you have to chisel/drill them out, they are made of plastic.

2. A siphoning-type of heat exchanger = sidearm type, which uses the hot water temp. to start a gravity flow thru the HX and heater. it is basically a pipe within a pipe, one line has the domestic hot water, the other has the boiler water flowing thru it. A plate-type HX cannot do that... it would require a circulator to cause flow thru it.
 
1. Hot water heaters have check valves inserted into the inlet/outlet fittings, to prevent siphoning (by temperature) or ghost flow of hot water back into the cold water line. difference in temp. between colder/hotter water causes the flow. As far as removal is concerned, you have to chisel/drill them out, they are made of plastic.

2. A siphoning-type of heat exchanger = sidearm type, which uses the hot water temp. to start a gravity flow thru the HX and heater. it is basically a pipe within a pipe, one line has the domestic hot water, the other has the boiler water flowing thru it. A plate-type HX cannot do that... it would require a circulator to cause flow thru it.

Gotacha on #2 - just never heard them called that

on #1 - wouldn't these integrated check valves serve the purpose of the in-line check valves you were talking about earlier??
 
Gotacha on #2 - just never heard them called that

on #1 - wouldn't these integrated check valves serve the purpose of the in-line check valves you were talking about earlier??


Yes/no. What I was referring to was on the boiler water side. Without the checks, any water that is in piping, etc. above the water level of the boiler would tend to gravity flow back to the boiler, creating a "air" pocket. That happens due to the fact that most OWB systems are open to the atmosphere.
 
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