I have a new 38YDB036 and an FE fan coil. It was installed in cold weather so the proper charge is still somewhat in question. He charged it as best he could to going by the heating chart supplied with the unit.
I notice that the frost always forms in bands but does eventually cover all but the bottom of the coil before it goes into defrost which I have moved back and forth between the default of 90 min and 60 mins.
Today the ambient air temp was 55 deg and it was still forming frost in bands. I notice that it also still forms frost when the OAT is 0-5 deg.
My last HP would never frost once the OAT was below about 15-20 deg but did still produce nice warm supply air. It also would not frost once the OAT was above 45 or so.
Would this tell you experts that the charge might be low?
Trying to compare a modern unit with the operation of an old unit is not a good idea.
Take your time & do it right!
But would you expect frost at 55 deg OAT?
it may have produced plenty of warm air because most techs wire up all the heat strips to come on anytime there is a call for heat. you would more frost the colder the ambient temp and the higher the humidity the more frost.
there should be a charging chart to charge the system in heat pump mode.
The heating check chart on the o/d unit is not to be used to adjust the refrigerant charge. The chart is a approximation of what pressure you would have under different ambient conditions. Adding refrigerant charge may lead to and overcharge. The only acceptable way to charge a Carrier heat pump in the heating mode would be, to weigh the charge in.
The frosting may or may not be a problem. Usually in the Mid-Atlantic the warmer the outside temps gets the R/H follows. Therefore frosting on warmer days may not be uncommon. Other than refrigerant charge what size is the Air Handler? If not match properly could increase the amount of frost..
The HP I am comparing the performance to was a Lennox HP19411 and was used in a duel fuel set-up with a G14Q3100 furnace for aux heat.
I replaced it with this Infinity 38YDB036 and an FE0500 fan coil. Installed 15KW of strips in 5KW increments.
And I love it!
I have thermocouples installed in several places and monitor the performance a lot. Excuse me if I am somewhat anal, I can't help it. I work in the power generation industry and do trouble shooting for a living. So I am used to taking lots of data. This is one of the major reasons I went with the Infinity control, I love the data the interface gives you.
I can give you lots of data from different ambient conditions including OAT, OCT, return temp, supply temp, CFM, suction line temp @ coil, you get the idea.
I would love to find someone to compare a like system with?
We are going to install the correct orifice that Carrier recomends and then weigh the charge back in and see how it compares.
We will also check the charge once the weather gets warm enough to run it in high cool.
Anybody have a like system?
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[Edited by Mod01 on 01-01-2006 at 05:58 PM]
As long as it is just frost don't worry about it. If your old Lennox HP didn't frost in the same manor it was probably overcharged. Since it was forming frost at 55 degrees it is probably slightly undercharged. There are methods for adjusting charge on Carrier heat pumps in heating mode. I suggest that your tech needs to contact his Carrier tech rep about this.