Hot water coming out of cold side - Contractor Talk - Professional Construction and Remodeling Forum

Eric K · 06-19-2009, 09:23 AM

Working in a house that has 4 bathrooms on upper floor of house. Bathroom 4 which is far away from other bathrooms is fine. Bathroom 3 get the hot the worst, scalding hot out of the hot side, bathroom 2 gets just warm water out of the cold, and the master will get luke warm then cold. Bathroom 2 - 3 go from being hot/warm to cold then back to hot/warm. But when the master shower is turned on there is no hot water at all in bathroom 3 but is fine in other bathrooms. We have had the boiler system replumbed to be isolated and a swing check put on the hot water tanks. The plumber seems to think it could be the master shower mixing valve, but the only way to access it is to remove marble tile. Before I go pulling tile I wanted to get some opinions on this. Thanks

willworkforbeer · 06-19-2009, 10:30 AM

I ran into something similar on a old two building motel, cant remember how I fixed it though. You could have had a circular hot system at one point on that system, maybe that got tied into the cold, sorry thats all I got.

**Leo G** · 06-19-2009, 10:45 AM

You have to look at areas that combine the hot and cold. A tempering valve, a shower valve like you mentioned are normal culprits. When something like a washer or an isolation membrane breaks it can let the two waters mingle resulting in a warm water in the cold water situation.

If you have re-plumbed the system it sounds like it would be likely that the shower valve in question is cross contaminating the cold water. Look for tempering valves on the toilets, occasionally they are put there to prevent condensation from forming on the holding tanks for the water closet. Good luck in you hunt.

BigReds · 06-19-2009, 11:08 AM

do those washrooms have automatic sensors for faucets? If so they also have a mixing valve which crap out (especially DELTA faucets). When those mixing valves go outta wack, the hole line is effected.

mrmike · 06-19-2009, 11:39 AM

You didn't state if this is a recently built house, whether the fixtures were just installed and not used yet ? .............If this is the case, bathroom 2 shower cartridge was probably put back in upside down, after they installed the valve. If they are new the other valves probably just need adjusting of the mixer, which sometimes takes alot of effort to get them just right.

Ron The Plumber · 06-20-2009, 03:45 AM

Start replacing the cartridges in the mixing valves, start with the shower, this is very common problem if you have Moen fixtures.

Eric K · 06-20-2009, 01:39 PM

Thanks for all the replies. To answer some of the questions all the faucets are newer Jado's, and the plumber had just replaced all the cartrages (sp) in them because they have very minor drips. The master shower was put in approx. 7-8years ago. The house is approx. 80years old. I think I will have the plumber get into the master shower mixing valve first, just going to a pita as there is no replacement marble on site. Let the scavager hunt begin......

**Leo G** · 06-20-2009, 01:51 PM

Replacing the cartridge shouldn't require any marble removal, just the escutcheon and some screws and a nut.

Eric K · 06-20-2009, 10:52 PM

Hopefully, if we can figure out what brand the valve is. No name on trim plate. Hopefully some more investigation will find it. Like I said I am only trying to "prequalify" myself so I have some knowledge on this when I talk to the plumber and to confirm what he suggested (mixing valve) Thanks all! When we find the problem I will post an update.

Ron The Plumber · 06-21-2009, 08:21 AM

Just because he said mixing valve, does not mean total replacement of it.

KillerToiletSpider · 06-21-2009, 07:43 PM

Jado valves are relatively easy to repair, the parts cost a fortune though.

naptown CR · 06-21-2009, 08:34 PM

This will happen a lot when remodeling and the plumber has set the new shower valve and caped off at the head and the valve is left on. It will allow water to mix across the hot and cold. If you have just put in a new valve and have it capped off at the shower head to leak test try turning off the stops if ti has them or removing the cap and making sure the valve is off.

BCConstruction · 06-29-2009, 08:43 PM

Yep as some have said your normal culprits are mixing valves that are letting by. Just try and isolate all but one at a time and try and track back to where the faulty setup is. Also have you tested to make sure you have balanced hot and cold supply pressures. Are you on a pressurized system or a gravity system? This can also cause back pressure and push hot/cold back into the other feed.