hot water problem

ScottMP

also check the washing machine connection. Cross connection some where is the culprit. Check the for a shower mixing valve that is being left open and a valve used to turn off and on a shower head/body spray.

Scott

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Brian Maffioli

Hot water problem

Maybe some of you fellow plumbers out there can help me out with this one. about eight months ago we completed the finish on a modullar home, now you have to pay attention to all the facts i am going to give you. the home is split into three seperate areas, lets call them "zones". Each plumbing zone has a seperate 3/4 hot and cold supply main with 3/4 recirc. now, two of these plumbing "zones" were pre-fab at modullar Co. the last "zone" is a master bath over a garage which was built on site and we plumbed soup to nuts on site.

Now, this is my problem. whenever end user turnes on any cold tap in house (big house six bath's) he gets a hint of warm water for 20 to 25 seconds and then tap returns to whatever cold water should normally feel like.

In the basement we have 2 superstor 60's and I brought back all three re-circ. lines to a common manifold and tied it in with a taco 005 bronze re-circ pump.

By the way in the rough in stage I went through painstaking
measures to make sure that all work was done right, our work and the modullar co. there were no crossed lines and re-circ. lines were plumbed in correctly.

Please someone enlighten me I dont have a clue on this one.

Steamhead (in transit)

Are there any

Moen faucets on this job? Certain Moens have been known to allow flow from hot side to cold side when recirc is used.....

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[Deleted User]

I don't know if this helps, but I had a similar problem where the hot water was backfeeding into the cold at the mixing valve. Also, do you have check valves at the recirc pump? Good luck.

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Rudnae

recirc h/ex?

Do you have any long runs on the recirc where the hot an cold lines are in close proximity? I have seen this where the recirc line is actually heating the cold water line, like a heat exchanger. Just my 0.02 cents.

Brian Maffioli

hot water problem

Yes, in fact all three of the common baths in the house have moen, moentrol valves and I had a hunch that this may be the culpret. but the master bath which is the bath that we plumbed in rough to finish has A Rohl t-stat valve with 3 volume controls and multiple heads.
the other two baths are both half baths on the first floor and all baths seem to be affected.
Not to leave anything out the master also has a whirlpool tub with a hand sprayer so there was a mixing valve installed on that also.

Larry Weingarten

Try turning...

... off the cold supply to the hot storage and then open any hot tap. If it keeps running, you know there is a cross connection. Then you get to find it ;~) The polysulfone cartridges from Moen fix the leaky brass cartridge problem.

Yours, Larry

Weezbo

Check against flow...?

on cold and recirc...?

cold checked on cold side of anti scald?

for sure the moen valves could have one upside down..

mark_101

cross connection

just something to think about. are there any tempering valves for the toilets.i have had a cross connection on these before. just trying to help.

ScottMP

Brian

how is the hand shower mixed ?

We've had to add check valves tos top this. Try turning off the mixer and see if that helps.

Let us know

Scott

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BigE

Its probably not mixing in new Moen cartridges. What the problem might be is the hot, cold, return lines were installed close to each other. The constant recirc. is heating up your cold line. See this alot in high rises where they pipe all three lines through one core hole.

JohnNY

I agree with BigE.

I'm seeing this problem more and more as houses get tighter and insulation materials get better.
The recirc line warms the bays in the wall where the cold water piping sits along with it.

Test this by shutting that recirc loop overnight and trying it out in the morning.
I'll bet the cold is cold right away.

Solve by adding a timer to the recirc so that it starts to run just a short time before your client's alarm clock.


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[Deleted User]

Binga!! Recirc return migration blues...

And now that everythings is finished, short of shutting down the C.R., they're going to have to live with it. We taught our best GC how to avoid the problem by keeping the hot and circ return lines in one bay and insulating if possible, and the cold in a completely different bay/area.

Did it on his next home and it works like a champ. It is now a standard "feature" of his homes... Makes him better than the other guys :-)

That's one of those things that doesn't come immediately to mind when roughing in potable water lines, which are typically grouped together. Until you get the "I have to run the cold water for a long time before it gets cold..." complaint. Then, it becomes all too obvious.

ME

laurence salvatore_2

hot water mystery

When I did my Dad's modualar (nights after work in winter) I hooked hot and cold to two 1/2" pipes amoung many that were poking through the floor and he experienced the same mixing thing. I thought the pipes went to the laundry but i turned out it was a toe space heater I didn't know about.