Mammoth Heat Pump

[blewbyu2]

Mammoth heat pump model g072hhk-f serial no. 02m293089 Water source heat pump. This unit is located in the basement parking garage of a 6 story building that is conditioned, ambient 65 - 70 degrees F. The load varies dramatically because it conditions a night club also located in the basement. Occupancy may range form 15 to 100 people. Located in Louisville, KY the outdoor temps currently are fluctuating from 20 to 60 degees. Original call is that unit has tripped high pressure safety while in heat mode. I was not the tech on this call. The invoice indicated that after inspecting the unit the charge was reduced. Next call evaporater frozen cooling. Previous tech increased charge. Now it's my turn ( woopie?!! ) anyway static pressure supply and return .3 inches wc, evaorater clean, blower clean, good loop temp, clean strainer. I recovered refrigerant and wieghed charge back in. Same results, High head heating 325-359 and low suction cooling 40-45. Superheat is excessive in both modes 30 degees plus, sorry no subcooling. Metering is cap tube with orfice. No literature naturally and Mammoth's web site is under construction. Oil logged evap or metering restriction? Because of construction of unit I can barely see cap tubes let alone access them. Any suggestions would be appreciated. Also I can't remember but I don't think there is any factory installed LL filter. Because of a limited time available on the call I may of overlooked some critical diagnosis. I'll shut up now and let you pros get me out of this mess Thanks

[The Doctor]

Cap tubes cuts the legs out from under my first suggestion, which had similar pressures but due to a txv sensing bulb line being shot. While it seems that the pros are still unavoidably detained...;) Is the air filter restricted? One time a Climatemistress, I mean, master (with auto reset HPS) got me out on a Saturday. The thing could not reject heat, and the remodeling/sheetrock dust was found to be...well, you know.

[blewbyu2]

Filters are spotless and evaporator is fairly wide finned and has been chemically cleaned although I don't think it even reqired cleaning. One thing I will add is that my delta t's were not too bad. 35 on heat and 25 cooling. Not perfect but tolorable. Although I have multiple blower speeds available only one can be utilized for both modes. I could change that with a relay but at this time I don't believe air flow is the culprit.

[Carnak]

I am not familiar with that model, but I am surprised it is only cap tube.

Get a complete set of readings, super heat, sub cooling, all the pressures, water entering/leaving, water flow rate or pressure drop across the coax water to refrigerant heat exchanger, air temp rise to go along with that static, amperages, voltage.

I don't have the tech support number anymore but maybe have all the information on hand and start by calling

Mammoth, Inc.
101 West 82nd Street
Chaska, MN 55318
(952) 361-2711

Maybe ask for tech support there, I can't remember if the tech guys are in minnesota or wisconsin.

[Carnak]

35F is a pretty high air temperature rise

I used to sell their residential equipment and it was TX valve. My entering water temperatures were 30 to 40F. Superheat they wanted to see was about 9F on those models.

[blewbyu2]

Good reponses so far. 16 threads so far to get back into pro forum, what a hassel. Anyway I've got to go install three Liebert humidifier tanks this morning and I'm sure by the time I return you guys will already have a solution and I will have won the powerball enabling me to repay everyone who has so generously contributed to this thread.

[lwarren]

High head, low suction, and high superheat would generaly indicate a restriction, but the high deltas on the air make this seem fishy. Need to see the subcooling. Also what is the head pressure in the cooling mode?

As Carnak said, get all of the readings you can!

[james mo]

The sympoms seem to indicate an indoor coil problem--Is the entire coil active? Take multiple discharge air temperatures accross the coil if you can. Take temps of the return tubes of the seperate circuits at the return header.

[madhat]

Is the blower wheel installed correctly? Seen a lot of Mammoths WSHP out of the factory with blower wheels installed wrong, some ran for years like this. PS if you have to turn it around, take the square head bolt out and replace it with a set screw. Adjust the set screw so the wheel will only slide on the shaft with the set screw aligned with the flat spot. Drill a hole thru the fan housing, and reach thru the blades with a long hex key to tighten set screw on the shaft.

[psychometric]

I didn't catch the entering and leaving water temps. I like about 70 in the heat mode, and about 80-85 in cooling. Water delta T around 8-12 degrees.