How to trigger two stage thermostat on commercial heating system

Steve Garson_2

I have an office with an HVAC system that heats with gas, with supplemental electric when required. I am trying to measure the wattage used when the electric heat is on, without getting a ladder to the roof, by measuring the current with an Amprobe at the breaker panel.

My question is: how can I activate the secondary electric coil to make this measurement, if the weather is not very cold?

Thanks,

Steve

nicholas bonham-carter

Many thermostats (such as a Honeywell Visionpro 8000), will have in the setup, a testing function, which will exercise any of the features.--NBC

bob_46

turn it up as high as it will go .

ratio

If it's wired up as the second stage heat, you should be able to pop the stat off the base & jump W2 to R. Probably need to jump G to R as well to being on the fan.

Empire_2

With out knowing the amperage of the fan/induced draft of the gas side, you cannot determine the load since your electric heat has to be measure alone! W/O a ladder, you aint measuring crap!!!!

ratio

You can get pretty close. Pull the stat off, jump the fan on, measure fan amps. Jump W2 on as well (keep fan on), measure amps. Subtract fan amps, if there isn't anything funny going on that'll be the heat strip amps. It'll work even if you have to fire the furnace along with the heat strip, just make sure to get the fan only separate. The inducer & control together won't add up to 10% of the heat strip amps. The blower is the only thing in that furnace that you'll notice compared to the heat strip. It might be running at different speeds for fan-only verses heating though.

Empire_2

Wow... So while I do understand the concept, are we sure that there are no corroded connections causing an incorrect reading or perhaps other things that cannot be seen unless at the unit? I guess my training is mute! I am surprised at what I am hearing or reading,...sorry....lol:-) Will you bet your rep. on that info? SWEI, I would at least expect from you in all theory, nothing is as it reads unless you can rule out all variables........... Well I guess I am over ruled. When and, or and if that building burns down will any one here say, "well we took all the measurements from floor level because we didn't have a ladder?" That is how bad things happen. Sorry I cannot pass on supposed to should have could have!

I am pretty by the book on this and do not mean to be disrespectful as I know everyone here has an opinion. Sorry if I bent someone the wrong way, but I will not waver from a possible electrical
error,......Which can cause untold mayhem.


Peace;
Mike T. Too many variables.

ratio

Eh, it just sounded like the OP wanted a guess at the size of the heat strips without slinging a ladder. I suppose I made an ASSumption... It's not how I would do a checkout though. Coming from an electrical background (been clean now for two years, yay!) I have a pretty good idea of what can go wrong.

Steve Garson_2

Yes, just wanting to measure amps. Nothing more at all. Thanks everyone.

Empire_2

Steven, Just my thoughts nothing more... Peace!

Mike T.

Empire_2

In addition.................................... Coming from me who burned myself with hot water when making Turkey soup over the weekend, but then I digress and as usual,............................ Don't wish to talk about it. Stupid mistake on my part and I would bet all of the people here would have said, "Watch out"..... Mike lol


Happy holidays everyone.
Mike T.

SWEI

Empire said:

SWEI, I would at least expect from you in all theory, nothing is as it reads unless you can rule out all variables

Not sure exactly what I am being asked here, but in short: @ratio described the easy route to an answer above.