While fixing our PTAC wall mount Carrier unit in sun room, I wondered I
SPDT capillary thermostat for heat/cool running on 220V AC. Unit contains
6KW rated heating element/heat pump. Is it possible to replace original
capillary thermostat with line voltage SPDT thermostat? Tired of replacing
original capillary thermostat at 70.00 a pop. Heating switch contact
up, p/n HH22UC075. Or I wonder if there is heavier Carrier substitute
On Sunday, October 12, 2014 12:17:26 AM UTC-4, Tony Hwang wrote:
Not sure what the question really is. If the replacement thermostat has
at least the rating of the original, it will work electrically. The rest
is if it's a different type, where does it sense the air? If the old one
has a capillary probe that sits in the air and the new one doesn't then
it may behave differently. There is also the issue of will it fit physically.
And finally, I guess the issue of modifying a UL listed AC, if you want
to get technical. I wonder if the reason they burn out is that the compressor
is starting to go and is harder to start? Maybe time for a hard start kit.
When weather gets cold heat pump does not come on,but heater is on.
Compressor (cool) side contact is always good. Maybe I should put in
spark suppressor across heat contact then... Was just thinking.
Capillary probe is sensing intake room air temp near the filter. . I was
thinking about extending 3 wires for the thermostat to wall mounted line
voltage type NO/NC SPDT type 'stat/ Actually another model of this unit
has this remote 'stat option kit. Maybe that is what I need, come to
think of it. Just exercising my brain for now.
This is Carrier PTAC wall mount they quit producing in 2009.
Heat pump and 6KW heat strip combo for heat/cool. Works well
for our sun room separate from house HVAC also Carrier.
Replacing thermostat is PITA, has to take cover off, control panel off,etc.
3 connectors. I was thing about extending those 3 wires to a higher wall
and use line voltage 'stat which is easier to get. Also I'm thinking
across heat contact to protect the contatcts from burning(which is the
issue) Snubber is
easy to jury rig. A resister and capacitor in series.
On 10/12/2014 1:37 PM, firstname.lastname@example.org wrote:
Bi metal is two unlike metal sandwiched together and they expand at
different rates causing it to bend. That is the types use is the round
Honeywell T-stats in many homes.
mercury expands in a tube or bulb. It can register degrees in a long
tube as an indicator.
Capillary is a thin piece of tubing with usually a bulb of some sort at
one end. As the material inside expand, it pushes a diaphragm and can
operate a tiny switch to make or break a contact. Refrigerators use
that type. Others for gas appliances have a bellows that can work a
valve to control the gas. No electricity needed.
The liquid inside is some sort of silicone than can take both high and
Follow up, I put in OEM replacement parts this time in ahurry but
I installed snubber across heat contacts and will see it helps.
Fixed the unit in a hurry and well, looks like we are in Indian summer
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