Need some help

[ascj]

Got a building with 76 wshp's. The one tenant is complaining about the one heat pump in there office making a long bang. They think it's going to come through the ceiling(hmm...exaggerate much). The problem is when the hp shuts down after a call for heat, the compressor shifts so bad it moves all the piping.

So the first time I looked at it, I noticed the hx was not bolted to the side of the unit. So I fixed it and it sounded much better. But the tenant is still complaining about the noise.

So I check it out again today. After a heat call, the compressor and reversing are de-energized and the compressor knocks abit. So I try jumping out the reversing valve and just cycling the compressor. Quiet and can be.

So my question is does anyone know off a simple fix to leave the reversing valve energized for about 30 sec after a call for heat? I was looking at ICM controls or a sequencer, but nothing seemed to do the job.

[klove]

I would have suggested a delay off timer, as you stated. ICM may not make them, but they are available.

[Airmechanical]

sequencer sounds good

wire the sequencer and the rv in parrallell

then when the rv de-energises through the stat, the sequencer will keep the rv energised through it's contacts until sequencer opens "after it's delay"


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[Octopus]

Just curious did u check the charge, amp draw, superheat/sub cooling?
Other than that what the other guys said delay on break wrapped around like a 9430 relay or something.

[ascj]

sequencer sounds good

wire the sequencer and the rv in parrallell

then when the rv de-energises through the stat, the sequencer will keep the rv energised through it's contacts until sequencer opens "after it's delay"


.

I was thinking that, but the problem is the control voltage is dc. Do they make dc sequencers or is ok to use 24vdc to the coil of the sequencer?

Then I was going to just wire it into the reversing which is 24vac, but the sequencer would delay it on also.

[ascj]

Just curious did u check the charge, amp draw, superheat/sub cooling?
Other than that what the other guys said delay on break wrapped around like a 9430 relay or something.

Can't check the charge. The way we check the unit's in supply td and water line temps. I just pulled it up on the BMS and it's running a 31 degree td and water is 75 degrees in/84 out. Filter and amerages were good the first day I was out.

[Airmechanical]

Then I was going to just wire it into the reversing which is 24vac, but the sequencer would delay it on also.


as stated on my last post

wire the sequencer parallel to the RV

this would avoid the delay on startup

and benefit on shutdown


as far as a dc sequencer, is the RV dc voltage?



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[klove]

Go to your local automation controls wholesaler, or any of several companies have websites where you can search for what you want (Newark, Digi-key, Galco, etc.) and tell them you want an instantaneous make/delayed break normally open relay of XXX coil voltage (needs to be the same voltage as the RV solenoid coil).

Wire common to one side of the relay coil, hot going to the valve solenoid now goes to the other side of the relay coil. The contact common terminal is fed from the voltage supply (assuming "R" on the 24 volt terminal block?) that feeds whatever used to energize the RV solenoid, other contact terminal goes to the solenoid coil. When the relay coil is energized the contact makes instantly to energize the solenoid coil, but delays on break to deenergize the solenoid coil. You can get them with fixed or adjustable TD's.

I made some assumptions about how your unit is wired in an effort to give some detail, but you can see the gist of where it's going.

[coolerinfrederick]

had a cust. complaining about a similar banging noise in a new hp we installed, went there twice and couldnt identify the nosie, after the second visit i heard it, thought someone was playin tricks on me, it was the non bleed txv check leaking when the system would shut off and trying to equalize, called the fact. rep. and we switched the valve to a 15% bleed type valve which cleared the problem up, it didnt do it all the time so it took a couple visits to catch it, according to the cust. it was always in the middle of the night, when i did here it, i was surprised to hear how loud it was

[Paul Bee]

11

[ascj]

So after thinking about some more and reading the suggestions from you guys, I think I'm going to use a 3 wire 24vac fan delay board. It has a 60sec delayed off.

I'll put "r" and "c" to the 24v transformer. Pull the rv wire off the main board and have on the "no" contact on delay board with "r" on the other side. Then have "g" on the delay board go to the rv hookup on the main board.

That should work, thanks for the help.

And by the way, all the controls in the unit are 24vac. It's the thermostat connections that are 24vdc. Why does McQuay do that?

[Airmechanical]

So after thinking about some more and reading the suggestions from you guys, I think I'm going to use a 3 wire 24vac fan delay board. It has a 60sec delayed off.


that same 3 wire delay is available with adjustable off delay time, anywhere between 6 seconds to 8 minutes off delay, the longer the delay the better in your case



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[just_opinion]

Can't check the charge. The way we check the unit's in supply td and water line temps. I just pulled it up on the BMS and it's running a 31 degree td and water is 75 degrees in/84 out. Filter and amerages were good the first day I was out.

I am just curious. Why not ?? checking systems.

76 units. And 75 of them are fine. Just happens to be one ???

I hope we don't reinventing the wheel, knowing that sometimes there is one lemon in an apple bastket.

Do we actually fix the problem. ??

So if a boy cannot walk, a doctor just simply gives hime a cane without diagnose carefully??

[ascj]

I am just curious. Why not ?? checking systems.

76 units. And 75 of them are fine. Just happens to be one ???

I hope we don't reinventing the wheel, knowing that sometimes there is one lemon in an apple bastket.

Do we actually fix the problem. ??

So if a boy cannot walk, a doctor just simply gives hime a cane without diagnose carefully??

The newer McQuay heat pumps do delay the rv. The older ones don't. The older units there are definitively louder on shut down when running heat. This tenant's unit is directly over his desk and he is a complainer(as per the landlord).

And yes I have had to install 2x4 insulation under other units and such to try to dampen noises. Basically this unit I don't think is any louder than the others, but the landlord is getting repeated phone calls about it. He said just do what you do to shut them up. I believe delaying the rv will. It can't hurt.

[ascj]

that same 3 wire delay is available with adjustable off delay time, anywhere between 6 seconds to 8 minutes off delay, the longer the delay the better in your case



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You dont happen to have a part number or anything.
Thanks.

[Airmechanical]

You dont happen to have a part number or anything.
Thanks.

i gave you faulty info sorry,

i got my projects mixxed up, the part i was thinking about was a delay on make timer, i used it on a project once to utilize two different fan motor speeds

you could always slap a standard trane delay fan relay in there, it has a 90 seconds off delay on it, wire it in parrallei like i was saying earlier

just remember however you wire whatever in, expect something odd to happen in defrost

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