Taco 5000 issue?

hankwylerjr · April 24

taco 5000 was leaking from adjustment valve. Swamped it out with a new customer now said hot water comes on for 3-4 minutes then goes cold. Left it sit does the exact same thing. He also has a watts 500800 recirculating pump denies any issues with that before changing taco 5000. Any ideas what’s going on here I’m stumped maybe water heater?

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hot_rod · April 24

Looks like a check valve in the piping, is there a thermal expansion tank on the water heater? Downstream of the check?

There is a specific way to pipe a thermostatic with recirc. Here is a pic and explanation.

Expansion tank could connect into the blue, cold water lines

hankwylerjr · April 24

@hot_rod he’s definitely an expansion tank and I checked it downstream but the thing is this was working good up until the leak over the weekend now it’s a problem

PeteA · April 24

could that be a reversed valve body or a clogged screen or check valve

hankwylerjr · April 24

@PeteA reversed valve? Are you certain maybe clogged screen but clean one was installed

hot_rod · April 25

https://forum.heatinghelp.com/discussion/comment/1853467#Comment_1853467

If the water is coming out from under the knob, then the stem o-ring has failed. That is unusual, so I suspected a very high pressure condition, caused by thermal expansion.

Cross connected would not be a cause of that, although the info on the cap looks like 230 psi? The pressure relief in the tank would discharge long before you hit that pressure.

It is a ASSE 1017 valve, so it should not have checks in the H&C ports, as 1070 valves do.

A wider pic may add some info to the mystery.

Joe Mattiello · April 25

is the expansion tank waterlogged? That would cause the high pressure spike and weakest link in your system O-ring failed. Have you inspected the old valve to see what caused the O-ring to fail?

If the new tempering valve is not working properly and the system has been working flawlessly for years, it’s pretty not the tempering valve.

You can call Taco tech support for additional support at 401-942-8000 and ask for tech support. Piqued my curiosity as to what the issue was; keep us posted.

PeteA · April 25

https://forum.heatinghelp.com/discussion/comment/1853476#Comment_1853476

I only mention the reversed valve because the limited info you have above doesn't say there is a flow issue but that you actually get hot water for a few minutes and then it flows cold and when you let it sit it does it again. So since this is a thermostatic valve I was wondering if the hot and cold inputs on the valve body could accidentally be reversed when it was installed (cold coming in hot side and hot coming in cold side) and cause something like this.

hot_rod · April 26

thermostatic valves need the hot inlet to be 15-25 degrees hotter than the mixed outlet or the valves will hunt around like that. There is usually a minimum flow requirement also. So if you set for 120f, supply 140 to be sure. Crank down the valve or increase the hot supply temperature to check that.

That might be a Cash valve, they show a 1 gpm minimum. Same symptom if the flow is too low, the valve will hunt around and not provide a stable outlet temperature. Open a tub valve or another couple lav valves and see if temperature stabilizes. You may need to keep the recirc moving 1 gpm to meet that minimum gpm.

Taco 5000 issue?

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