Carrier package HVAC unit with electric heat (10KW)
I have a heating problem one bank of my heat strips 5KW is not working. I have found the problem, the thermal fuse is open. It is a Microtemp 404204A there is also a number 98C. Where can I find a replacement for this part? Any info would be appreciated.
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Is this a heat package inside a Goodman air handler? If so, it is probably at least a 10kw (two element) unit and it sounds like the first stage is not coming on. Of course it could also be a 15 or 20 kw heat package with multiple heat stages, I have no way of knowing.
Sometimes the second and subsequent heating elements operate off of the 'sequencer' of the previous stage. Not always though. If its a regular furnace it should have a terminal strip with R W G Y and C on it. With the thermostat calling for heat, check for voltage (hopefully you have at least a cheap DVOM) between W and C. If 24 vac is present, find the first stage sequencer by looking at the schematic on the air handler door. Follow the wire on W1 in the diagram to the sequencer. After locating the sequencer, check for voltage across the coil....which should be the same as W and C. If there is 24vac there and it has been there for 45 seconds, the sequencer switch should be closed which then energizes the heating element. Without an 'amprobe' (clamp on ammeter) it is difficult to determine if current is flowing through the heating element.
If you can verify that the first stage element now has 240 volts across it, but there is still no heat about all you can do is turn off the power ---------- (IMPORTANT!!!!!!)-------- and remove the high voltage wire from one end of the element and use an ohmmeter (if you are lucky enough to have one) to verify that the heating element is in fact good or not. Resistance shown on the ohmmeter shows it to be good, no resistance shows it to be open and possibly the culprit.
Of course in series with the element is always a 'high temperature cut out' that could be causing the element to not heat. The same technique is used to check and verify each sequencer and element in the furnace. Its a whole lot easier if you have an amprobe.
Remember you are in a high voltage environment which is very dangerous to the untrained individual. Do not attempt this if you are nervous around electricity !!!!!
There is a whole lot more than can be written in a concise manner but this may get you in the ballpark....
You should befriend an HVAC guy.....
You can use the existing air handler for a heat pump condenser unit up to 3 tons. The line set, evap coil are fine for a heat pump. The electric heat strip issue can be another problem, you can put several different size strips in depending on what may be needed where you live, the power requirements will differ with each heat strip, for example a 5KW (5000 watt) heat strip requires a 2 pole 30 amp circuit for heat strip and air handler combination.
In general, when more than one heat strip is present, one is used as primary heat, and the second one comes on if the primary does not prevent the temp from falling.
Another set up is, yes there can be a time delay in the system. it usually takes a few minutes for the second set to energize.
Since you did not state if this is a heat pump, i'm limited in my response at this time.
Hope this helps.
1. The units should match up without a problem.
2. You will need a 40 or 50 amp breaker for the A/H and 5 KW heat strip. You will probably need a 20 or 25 Amp for the condensing unit. I would check the FLA (full load amps) rating on both units, total them and install a breaker with no more than 20% more rating than the total. You can install a small box at the A/H with a breaker for the A/H and one for the condensing unit.
I would say this is around 75 amps of draw at max for both the compressor and heat units. . Therefore--at least 90 amp breaker, and probably 100 amps for good measure, and at least #4 or #2 wire to the unit.