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Gemstone
Premium Member
join:2000-12-20
Long Island

Gemstone to SparkChaser

Premium Member

to SparkChaser

Re: Honeywell Round Thermostat

Thanks for all the responses...

The reason I ask is because the Honeywell Model RTHL3550D thermostat I want to buy says it runs on 24VAC (actually it says 24V)... I want to be sure my 32VAC will not cause damage...

ArgMeMatey
join:2001-08-09
Milwaukee, WI

ArgMeMatey

Member

said by Gemstone:

The reason I ask is because the Honeywell Model RTHL3550D thermostat I want to buy says it runs on 24VAC (actually it says 24V)... I want to be sure my 32VAC will not cause damage...

Contact Honeywell pre-sales support and ask them what the acceptable range is. I've done this using online chat so I had a record of what I was told.

You can also find your control transformer and see if it has multiple outputs. It would be unusual to have a 32 VAC transformer, but it's not out of the question that a nominal 24VAC xfmr would put out 32 VAC, especially if it's older and manufactured to looser tolerances. Or there's a slim chance it has more than one tap.

For my doorbell I have a 3-tap that does 8/16/24, but my HVAC transformer is fixed. I just measured it with an analog meter at 24.5 VAC, although it is currently loaded by the zone controller.

If in doubt, you can probably swap out the transformer cheaply as long as it's not part of the furnace or some other controller.

Gemstone
Premium Member
join:2000-12-20
Long Island

Gemstone

Premium Member

said by ArgMeMatey:

said by Gemstone:

The reason I ask is because the Honeywell Model RTHL3550D thermostat I want to buy says it runs on 24VAC (actually it says 24V)... I want to be sure my 32VAC will not cause damage...

Contact Honeywell pre-sales support and ask them what the acceptable range is. I've done this using online chat so I had a record of what I was told.

You can also find your control transformer and see if it has multiple outputs. It would be unusual to have a 32 VAC transformer, but it's not out of the question that a nominal 24VAC xfmr would put out 32 VAC, especially if it's older and manufactured to looser tolerances. Or there's a slim chance it has more than one tap.

For my doorbell I have a 3-tap that does 8/16/24, but my HVAC transformer is fixed. I just measured it with an analog meter at 24.5 VAC, although it is currently loaded by the zone controller.

If in doubt, you can probably swap out the transformer cheaply as long as it's not part of the furnace or some other controller.

I contacted Honeywell via their online form... Waiting for a response...

The control transformer is part of the oil burner (Riello)... It is marked as 24VAC output... Only has 2 terminals... I measure 32VAC across the terminals...

ArgMeMatey
join:2001-08-09
Milwaukee, WI

ArgMeMatey

Member

said by Gemstone:

The control transformer is part of the oil burner (Riello)... It is marked as 24VAC output... Only has 2 terminals... I measure 32VAC across the terminals...

In that case, you might also check a site like heatinghelp.com.

There are probably a million Riello oil burners with identical transformers and all kinds of Honeywell stats, so chances are somebody there has already scratched this itch on their own head.

Best to you.

Gemstone
Premium Member
join:2000-12-20
Long Island

Gemstone

Premium Member

said by ArgMeMatey:

said by Gemstone:

The control transformer is part of the oil burner (Riello)... It is marked as 24VAC output... Only has 2 terminals... I measure 32VAC across the terminals...

In that case, you might also check a site like heatinghelp.com.

There are probably a million Riello oil burners with identical transformers and all kinds of Honeywell stats, so chances are somebody there has already scratched this itch on their own head.

Best to you.

Thanks!!

SparkChaser
Premium Member
join:2000-06-06
Downingtown, PA

SparkChaser to Gemstone

Premium Member

to Gemstone
said by Gemstone:

The control transformer is part of the oil burner (Riello)... It is marked as 24VAC output... Only has 2 terminals... I measure 32VAC across the terminals...

I think it's what alphapointe See Profile said; it's unloaded, your meter may be off. Peak voltage on 24VAC (RMS) is 34 volts.

FWIW, I did what you are doing. I replaced the round one with a new HW stat similar to what you are doing. In my case it operates a relay but the voltages are the same.

Gemstone
Premium Member
join:2000-12-20
Long Island

Gemstone

Premium Member

said by SparkChaser:

said by Gemstone:

The control transformer is part of the oil burner (Riello)... It is marked as 24VAC output... Only has 2 terminals... I measure 32VAC across the terminals...

I think it's what alphapointe See Profile said; it's unloaded, your meter may be off. Peak voltage on 24VAC (RMS) is 34 volts.

FWIW, I did what you are doing. I replaced the round one with a new HW stat similar to what you are doing. In my case it operates a relay but the voltages are the same.

My meter is a fairly new FLUKE #115 True RMS Multimeter
skutflut
join:2001-11-09
Ajax, ON

skutflut to ArgMeMatey

Member

to ArgMeMatey
Just a thought... make sure the voltmeter you are using is an RMS meter and set to read peak volts.

jack b
Gone Fishing
MVM
join:2000-09-08
Cape Cod

jack b to Gemstone

MVM

to Gemstone
said by Gemstone:

...The reason I ask is because the Honeywell Model RTHL3550D thermostat I want to buy says it runs on 24VAC (actually it says 24V)... I want to be sure my 32VAC will not cause damage...

The thermostat "runs" on the two AA batteries, it only switches the 24v (32v in your case) circuit, open/closed. If the batteries die, so does your heat.

Add the thermostat to your annual smoke/CO detector battery replacement list, and you'll be good!