Goldline GVA-24 valve actuator is leaking

Shut off unit then turn off water to house at water main out side. Drain water heater remove old valve install new

I had to replace mine a few years ago. Just look on line. Search for pressure relief valve, or add solar. You will get a lot of responses. Comparison shop and buy. On line auctions work well also.

The "R" terminal on the back of the stat should be 24 volt supply to the stat. For a heat pump, when the stat calls for heat, the "W" terminal goes hot (24 V) and should actuate the reversing valve and start the outside unit for heat. when the stat calls for cooling, The "Y" terminal goes hot and starts the outside unit without the reversing valve. The heat strip is used to temper the air while the outside coil is defrosting when in heating. You need an OHM meter to test for a short in the heat strip. A lot of installers are wiring it to heat all the time when in the heating mode if the heat output is too low on really cold days. Try jumping "R" to "Y" and the outside unit should start. Disconnect the heat strip from power while testing. This is really brief, its a big subject. Good luck.

10-30-12
Cost calculations for recirculation system vary widely.
These systems cost more, and they cause higher operation cost of water heater.

1) When pump is OFF, then hot water is no longer leaving the tank.
Most recirculation systems have choice of timer for setting specific times of operation, or thermostatic operation that activates pump when sensor detects temperature less than 90 degrees
BUT...

2) Condition of plumbing is suspect here because you are not receiving fully 90 degree hot water from the recirculation system.?.

Bad single-handle faucet cartridge, or bad recirculation check valve, are causes of crossover. Clean recirculation check valve with white vinegar. Replace worn faucet cartridge.
Test for crossover.
http://waterheatertimer.org/Crossover.html

3) There are other suspects, such as water leak.
Drips, broken pipe, bad TP valve.
Turn off all taps and put ear against pipe to listen for running water.
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html#listen

4) High costs: Lifting single-handle faucet in middle will immediately cause cold water to enter tank. Even if no hot arrives at tap, because the cartridge is drawing both hot and cold in equal amounts when handle is lifted in middle.
Today it is more efficient to install dual-handle faucets so tank is not receiving constant dose of cold water when single-handle faucet is not used correctly or tediously.
http://waterheatertimer.org/9-ways-to-save-with-water-heater.html

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

On the Goldline controllers, the check sensor light flashing means the sensor on the roof is either bad, disconnected or shorted out. When the check sensor light is solid on, that indicates it is the pool sensor. Check the wiring from the controller to the sensor on the roof. If the wiring is not damaged, most likely you will need to replace the sensor. You can check the sensor with an ohmeter, it should register 10,000 ohms at 77 degrees.

First, find out if you have a leak.
Turn off all water faucets inside and outside.
Record water meter register with camera.
Wait several hours.
Record water meter register again, and compare photos.
If you have a leak, contact city water department and report leak so bill can possibly be adjusted.
Ask city water department what they suggest.

If you had certified plumbers look at problem, it would be a guessing game for internet plumber to start listing things.

My guess would be crossover on single-handled faucet that runs the hot water into cold pipe that is filling the swimming pool that is leaking. But you might not have a swimming pool.
http://waterheatertimer.org/Crossover.html

Another guess would be a leaking TP valve that drains directly into a sewer vent line.
But certainly the plumber checked the TP valve.
http://waterheatertimer.org/How-to-replace-TP-valve.html

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if you have a gate valve on the unit from the hot water tank it could be as simple as the valve on the gas system being clogged going to that bathroom,, from how it is described it sounds like that would be the problem check to make sure all valve are not stuck in the on position ans change the valve if it is frozen in place

Remove the wires from the gas valve and call for it to light. While it is trying to light, take a voltage reading on the wires that go to the valve. If it is sending voltage to the valve and it won't energize the valve then the valve is defective. Just make sure that the valve is being told to come on. It could just be a limit switch. Double check the manual reset limits also before doing the vavle check. Hope this helps.