Scalding shower from shared boiler system in condo complex.

[Mike Roberts]

I just purchased a condo in an old complex that my daughter is living in until the graduates college. Once she’s finished, I plan to turn it into a rental. The problem we’re having is that we share our hot water from a boiler system that supplies at least 8 units and you can’t get through a shower without it scalding you at least once. The association basically says that there’s nothing they can do and it’s probably a faulty mixing valve which I’ve already replaced twice. I’m worried that I can’t rent it in this condition as I’d hate for a child to get burned... Any suggestions? Thanks!

[Jim Goebel]

@Mike Roberts

Sure Mike.  I'll donate my problem solving brain best I can.  

1. Firstly, is this unique to that one unit, or do they all experience it?  Please comment on that first.  If you don't know the answer to a question it'd be helpful for you to comment on if you can get that info.
2. Next question - you alluded to this issue being intermittent in nature.  Have you noticed any outside stimuli (for instance, the use of other fixtures elsewhere in the building/unit) that cause this, or certain times of the day?
3. Next question - does the boiler supply just hot water or does it also provide radiant heating type of solutions throughout the building?
4. Finally - what do you know about your boiler, specifically with regards to how its designed.  Is water constantly circulating or does it work more like a hot water heater (ie water sits in pipe for some amount of time)?  The cause of this might be related to the above if signs point to the boiler.  

Just not knowing my follow-up capacities (more of an attention thing than anything) here is where my mind goes regarding the problem solving......  I'd get the answers above before honestly even reading the below but it will at least 'connect' the info gathering and decisions regarding what your best options are.

If it is a problem unique to this one unit, then the hypothesis of the mixing valve may be apt.  From what you've described though - this would need a hard look before proceeding (again) as something seems fishy because you mentioned it has already been done a couple times.  If it is unique to your unit but there's say a long pipe run between your unit and the next 7, say, in the cold, then I could see that being the one exception to my mind going to an issue with your unit.

If it's a problem in multiple units that kind of points more to your boiler or overall system design.

The intermittent nature answer starts pointing you along the track of the actual cause, perhaps.  Any number of things could be happening and I'd prefer to come up with hypothesis there until further info is provided.

If the HOA etc does not openly provide the above info, and say it is an issue with a more comprehensive boiler related/design issue, there should be some recourse for you. Befriend the maintenance person if possible :)

The only way to 'solve' this if its a boiler/comprehensive system design issue, that I can think of, would be getting creative with some sort of a basic heat exchanger system that essentially takes some of the excess heat and 'transfers it' somewhere other than the water.  Or getting a dynamic mixing valve (not your standard variety) that has its own built in control system, that responds to temp differences instead of just being a mechanical valve.  I'd have to research what's out there for that.  I do suspect there would be something but you'd be talking about a little project there.