Timer

[Deleted User]

has a WHOLE bunch of dependable time delay relays. They have one universal model that can be programmed for whatever operation suits your fancy. Delay on make, delay on break, repeat, whatever.

Instead of that, how about a 3 way bypass valve that would receive the call for heat from the FCU's and bypass the buffer tank, thereby quickly increasing the supply water temperature to the FCU's. Might still cause short cycling if the load is less than the source tho...

Just thinking outside the box.

BTW, who's GSHP are you using, and what is the max temp you can get out of it?

ME

Jeff Lawrence_25

Timer

I have set up a water-to-water WSHP for a customer, complete with a ~95 gallon buffer tank. He’s a retired mechanical engineer that designed the system and I’m simply installing it. He’s real pleased with the set up except for a couple of minor problems.

First off, the WSHP would run for 45 seconds to 2 minutes and shut down if there wasn’t a call for the zones to be running (heat or cool). We solved this by tying the SR503 dry contacts into the WSHP. This way, it only will run if a zone is calling. The on-board controls set up the changeover temp and water temps.

Now when it calls, the heat pump will turn on and circulate whatever temp water through the lines that’s in the tank. If that water has dropped to 95° and the hydro-air AHU comes on, it’s going to feel cold. That’s a good temperature for the radiant zones and the tank will come up to temperature easily until the AHU comes on.

What I’m looking for is a decent and long lived timer that will allow the WSHP to run for 15-20 minutes even after the contacts in the SR503 have opened up. Some of the delay on break timers I’ve used in the past don’t seem to have a long life. Any ideas?

Jeff Lawrence_25

As I recall

it's a FHP. I thing the max temp is 110° but I could be very wrong.

This job has been near snake bit and that doesn't include the snakes we've found in the basement/crawlspace.

R410 WSHP had a R22 high pressure switch in it to start. Warranty replacement.
Hydro air handler (forget which brand) is a 230 volt unit with 10kW heat strips. It had a 110v motor in it. Kinda stunk up the house, ya know?

Owner did NOT want any strip/aux heat in the AHU. I stood firm and said you will got it or find another contractor. When we found the bad high pressure switch, he didn't thank me exactly but he said he was happy he had thought of it....