ReplyWhat are the entering and leaving water temps? Basically what I'm getting at is: what is the approach of the unit?
Regular Guest
I have a GEHB042.....heat pump that is having problems with high head pressure. The suction pressure seems to be fine. Eventually it shuts down when the source water reaches 100 degrees or above. . Trane is telling me that these H.P's are good to 115 degrees incoming water. The spec sheet for the unit says 95 degrees. As I continue to work on these HP's, I just don't know what to believe. I've had trouble with this unit before. The cond coil has been replaced and that helped for a while. I know it's not overcharged as I had to recover and weigh it back in after I serviced it. The gpm is ok as I had the system balanced to specs. I'm not sure what else to look at. I keep reading on this site about these WSHP's and how Trane is having a lot of trouble with them. I'm not very pleased....I have 44 of these H.P's in this building, and half of them I can't even get to. Any suggestions would be helpful. Thanks.
Professional Member*
What are the entering and leaving water temps? Basically what I'm getting at is: what is the approach of the unit?
Saving the world...one service call at a time.
Regular Guest
Depending on the outside temps and what time of day it is, the entering water temps are between 95 and 104 degrees, and the leaving temps are around 115 degrees. The highest I have ever seen the geo loop entering the heat pumps is 107 degrees.
Regular Guest
Depending on the outside temps and what time of day it is, the entering temps are between 95 and 104 degrees, and the leaving temps are approx 115 degrees. The highest I have ever seen the entering temps is 107 degrees, and that was about a full week of 90+ degrees outside.Originally Posted by mallron
Professional Member*
Ok, what's the liquid line temp as compared to the leaving water temp?
Saving the world...one service call at a time.
Professional Member
does it have piston?txv?
Regular Guest
At the compressor, it was about 224 degrees. Unfortunately, I can't reach inside to get a temp at the coil. These units are impossible to service unless you take them down and disassemble them. The leaving temp is around 110 to 115 degrees. I think I know what you're getting at. Just an FYI, the coil was replaced about 4 months ago. It seems to me that I'm not getting any heat transfer. When I replaced the coil, and while it was on ground level, I did a test run and ran the unit with hot water (105 degrees) and it ran great. I ran it for about and hour. With the hot weather lately , it has been shutting down. This unit is mounted about 25 feet high against the ceiling. It's fed with return air from a main AHU of about 50-70 degrees depending on the time of day. It is not warm up there at all. It does have an expansion valve. Could that be causing some issues? It appears to be original with the unit. I can't think of anything else.
Regular Guest
TXV.
Member
I'm curious why you replaced the coil?
Was it fouled (dirty)?
You are running at the edge water inlet temps, most rated to 110F @ 3 GPM per ton. Increased water flow will help.
High air flow will also add to the load.
Regular Guest
The original coil was fouled. When I installed the new one, it seemed to correct the problem. I don't believe it is fouled again as I have been monitoring the water quality throughout. The water flow is at the recommended specs. The building has 100% outside conditioned air running through a heat exchanger in the main AHU, going to each heat pump.
Professional Member
CHECK TO SEE IF TXV IS LOCK UP.IVE HAD ON WATER SOURCE HEAT PUMPS TXVS LOCK UP AND SUCTION PRESSURES GOOD BUT HEAD PRESSURE HIGH I REMOVE THE BULB AND SEE IF PRESSURE GET BETTER
Professional Member
THEN IF IT WAS TXV REPLACE IT
Regular Guest
I did remove bulb and head pressure went down. If that's the case, doesn't that mean the TXV is good?
Member
I suggest a data logger on EWT & LWT you need some exact numbers.
You are making too many assumptions. It sounds like a water problem be it temp, flow, or fouling.
Professional Member*
Is this system just Geo or do you have a cooling tower, If it's just geo sounds like you don't have enough tube in the ground, or if it has a tower I would lower your water temp.
We don't ever let it get higher than 90deg.
Professional Member*
yep, seen it a million times
It's hard to stop a Trane. but I have made one helluva living keeping them going.
Professional Member*
both scenarios are the common reason customers don't like water scource and have issues. there is a lack of engineering and design in the loop.
It's hard to stop a Trane. but I have made one helluva living keeping them going.
Regular Guest
What you are describing looks to me like a combination of high EWT and low flow.
A typical wshp setup runs about a 10-11 degree delta T on the water temperatures when in cooling.
Some people like to push for 15 degrees but you don't get much more cooling from that slower water flow and the compressor power consumtion increases. That means the compressor is working harder = higher head pressure.
This summer continues to be a tough one on cooling equipment. High ambient temps, water temps and EAT are killing WSHP all over the country.
If the EWT is toward the top end of the unit tolerance (95 EWT is higher than average)you can compensate by increase the water flow rate. Yeah, this increases loop pump power consumption but will reduce nuisance trips on the units.
This is going on the idea the unit is OK for service.
Professional Member
whats the supereheat at the point you removesd the bulb? your looking for about 6 to 8 degrees F. the check at the inlet of compressor, you might have a charge issues or air in the unit.
If you cant cool it
HEAT THE Hello out of it
Professional Member*
This thread was started in August, 2010. Let's hope somebody has solved it by now.
Posting Permissions