Water in multi family goes from warm to hot

MikeMono

We just put a water pressure pump in our apartment building and a few tenants are complaining that when they shower the water don’t stay regulated and goes hot and cold. My Tac239 Temperature reading is set at 130 degrees but I see it fluctuate from 90-160. Could that be a sign to change the temperature Pressure 

Intplm.

@MikeMono
What was happening before the pump installation?
Why was this pump installed?
You say the temp is fluctuating?
What is the pressure setting on the pump?

MikeMono

Hi, I installed a pump cause the water pressure coming from street after the RPZ was 38 pounds and the pressure on the 6th floor was almost nothing.

the pressure is set at 50 psi and fluctuate and cycles between 45-60 psi on that setting

EdTheHeaterMan

Yea, I don't think coincidence happens all that much.

1. You have no problem or complaints
2. You get a new pump
3. You get problems and complaints

It may be as simple as something getting lodged in a valve that regulates the temperature/pressure somewhere. Whenever I make an adjustment or repair to an old water piping system, there is always some debris that gets dislodged from disturbing the pipes. Check to see if something got some smutch in there somewhere.

(SMUTCH is a technical term Some Material Unlodged To Clog Hotwater pipe and other things)

MikeMono

Hi, I did have a lot of complaints ..this is why I got the pump..

EdTheHeaterMan

Did you find anything smutch in the valve?

hot_rod

Is the TAC a mixing valve at the water heater? A multi unit really should have a thermostatic or motorized mix valve.

And if you do have a mix valve, the pressure fluctuations could be blowing its mind, depending on the type of valve.

MikeMono

I do have a mixing valve

MikeMono

Tac239 w

hot_rod

An older valve? I didn’t think Schneider had any ASSE 1017 valves?

MikeMono

I have a mixing valve and the TAC239 temperature regulator thermostat set at 130 and it fluctuates ..could that be bad separately?

yellowdog

if the water temp is consistent going into the mix valve and just the output temp varies it will tell you the mix valve is bad.

hot_rod

Best I can tell that is a motorized globe valve. Could be the actuator or sensor is bad.

A true ASSE 1017 mixing valve is required to maintain a stable outlet +or - 3 degrees, depending on its size. Regardless of a change in incoming cold or hot water temperature.

Mark Eatherton

In my 50 years worth of experience, this fluctuation on older building can be coming form numerous problems. More questions than answer, but they have to be answered before finding cause(s).

1st, unless this is a REAL old building, where the tub outlets are below the rim of the tub, the RZP does NOT need to protect the building as a whole. This is due to the lack of understanding on the water authorities part, and their easiest out is to cover ALL the bases, by having you (incorrectly) apply the RZPBFP at the buildings inlet. In 99.9% of the cases, the ONLY place you need an RZP would be at the boilers make up connection.

2nd, why is the incoming water pressure so low (excluding the RZP misapplication). What's the pressure at the street (water authority SHOULD know, based on hydrant pressures)

3. Do you have DHW recirculation system in the building? Is it a constant run circ pump or does it cycle based on return temperatures and or time of day? If it cycles, is there a functional (don't assume) check valve on the circ return?

4. Why two mixing assemblies at the POG (point of generation)? Was scalding an issue before? Having two will cause them to fight each other, causing major fluctuations.
5. What is the DHW source (I assume boiler, with indirect heat exchanger, like an Everhot?)
6. Is there a storage tank as a part of the DHW package? If yes, how is it piped?
7. When does the highest number of complaints occur? During peak usage (6 to 8 AM or 5 to 7 PM) or randomly throughout the day?
8. What type of fill valves are on the toilets? The old ball and arm type, or the cup and tower (Fluidmaster) type?

In order to track down the fluctuations, you will have to have a good multi channel temperature data logger (see Hobo data loggers), or plan on spending 24 hours taking lots of readings every thirty seconds, whichever is easier :-).

You will need to monitor the water temperature between the POG, after first mixer, after second mixer going to load, circulation return and boiler supply temperature. If the POG and all of its mixing valves prove solid (reasonably so), then the problem is most probably a bad check valve on the CR that is letting cold water charge backwards, headed to the POU (point of use) causing major fluctuations at the POU.

I mentioned toilet ball cocks because the newer ones go from closed to wide open in a heart beat, and from wide open to closed is the same amount of time, setting up pressure fluctuations that cause temperature fluctuations in the shower. If the change in water temperature is more like a roller coaster ride, it is probably the check valve in the CR causing the problem, or a cycling DHWCR pump will also cause the same. Sometimes you can choke flow at the toilets shut off valve, or on the old float and ball type, adjust the arm drop screw to lessen the pressure drops created by the fill valve.

Get the answers to these questions, and we will either get an answer or cause more questions to be asked.

ME