commercial hot water system help

[perrycat]

I'm a maintenance tech for a property that has aprox. 1000 units, 3 seperate boiler plants, and it's built in the early 70's. I have constant service calls for water temperature fluctuation mainly in showers, the faucets never seem to get a complaint. This problem also seems to be happening at all 3 sections of the property, each section has a boiler plant for heat and cooling and domestic hot water.

All the units have the same tub and shower valve, they're Price Pfister with integral stops on each one ( half the time the stops don't work anyway) and they're washer type valves.

People as of late have been allowed to put in their own laundry washers and dryers, so maybe half to three quarters of the units have a washer dryer now, and when it was built they all had a laundry room with pay washers and dryers ( those are still there BTW)

I went to one building and on a hunch, used a gauge to check the water pressure from one of the laundry machines in the laundry room. The hot was 115 PSI ( I know that's super high I guess.....thermal expansion maybe?? most people were at work at that time) But the cold water was maybe 55 PSI.

So, question to you if you could give er a shot, is it possible that the water is "fighting" each other whenever anybody opens up the shower valve? I read something about a check valve that you put on the recirc line, and we don't have any on any of them that I've seen. Where would you locate that anyway? in the boiler plant right after the recirc pump?

Also, I've had this maybe hair brained idea that it could be because the washers in the valves are all so old, integral stops included, that maybe somehow the washers are like flipping back and forth somehow inside the shower valves, and somehow stopping the flow a little and then flipping back and the flow gets stronger again....is that possible?

One last one, and I REALLY hope it's not this, is that is it possible some plumber sometime in the past, even way past, crossed a hot and cold line in a repair and how could you track that down? that seems like that would be a real night mare, but it's happening in all 3 sections so I don't think that's what it is.

Well thanks for reading all that and thanks in advance for any input. These calls are driving me nuts....I will say that today I went on one and what had happened is that on the integral stop on that shower valve somebody only cracked open the hot side and the cold side was full blast....I rebuilt the shower valve and put the hot all the way open again and it's real strong now, I think that one I fixed...but I wish there was just one culprit and I could find it and fix it, heat exchanger, balancing valve whatever.....that's another thing....if I just said " you need a new shower valve" on every one and we put in pressure balanced valves, would that cure it for that specific apartment? Which are good strong really long lasting valves to use? I would like to keep em all the same so I dont have to have a plumbing supply house in the parts shop.
Steve

[jadnashua]

This is a guess...the valves that are in the showers are not pressure balanced or thermostatically controlled. With that many people, the pressure is probably fluctuating, which changes the hot/cold balance. That is exactly what the pressure balance valve is designed to help prevent, or at least keep from scalding or freezing the person in the shower. Are the old pipes copper or galvanized? If galvanized, they may be on their last legs - it might be repiping time.

[perrycat]

jadnashua, thanks. And that's right none of the Price Phisters in there are pressure balanced valves. This is great, it's time for new ones anyway, so if that cures it, then it's only a matter of getting them to approve a new shower valve for each one each time.

One of the main reason's they've been using a plumbing contractor for replacing shower valves is time...it takes a long time to shut off a section, drain down the system, etc...and we each have maybe 8 or 10 tickets a day to do. I've been really thinking about getting one of those Ridgid "pipe freeze" things, and a pro press. So, with those two things, I could do them, and not shut off the water to a whole section and it would be really quick. The money they saved because I get paid by the hour, versus probably $600 or more, whatever it is I don't know what they pay for a shower valve replacement....would be fantastic.

Also, they're going to have to start thinking of doing something like that anyway because all the fan coil units most of those have old gate valves and when you have to bleed out a fan coil so people can get heat or cooling, those valves are all either frozen or dropped gates too mostly. So, to me, it would look great in a year's time to show you cut your maintenance costs like crazy. I'm just still a little nervous about those pipe freeze gadgets, tha'ts why I wouldn't want to solder, and just use a pro press.
Steve

[srdenny]

Perrycat
Do your boilers have expansion tanks on them, and if so, are they original to the buildings?

[perrycat]

Perrycat
Do your boilers have expansion tanks on them, and if so, are they original to the buildings?

Yes they do, and yes they're the original. But the DHW comes from a heat exchanger that's seperate physically from the boiler water.

[Randyj]

I'd have some serious concerns about running 115 psi on the HW. Sounds like a check valve allowing the pressure to build up and in dire need of an expansion tank.

[perrycat]

I'd have some serious concerns about running 115 psi on the HW. Sounds like a check valve allowing the pressure to build up and in dire need of an expansion tank.

Thanks, that might be it. The engineering majician is supposed to be coming out soon to check it out, so now it's off my back except trying to explain to customers why they can't get normal water for a shower and they pay as much as they do....putting myself in their shoes, it's not alot to ask to have a decent working shower