Honeywell Round for millivolt

Jeff_17

I was using a Honeywell round TS86A for my one pipe steam system. Gave that old one to my father-in-law for his system and bought a Focus Pro 5000. Bad move. Worked terribly. So, I bought a new Honeywell round. Problem is this...If I set the therm at let's say 68...the boiler kicks on but does not go off until it is at about 71 degrees, then overshoots SLIGHTLY. It will kick the boiler on at about 67, so it starts our great..but finishes BAD. No matter what temp I set it for. Always stop about 3 degrees AFTER the set temp. The old one worked GREAT... now what? Should I return the one I just bought...defective? or some trick to know before I go back to the dealer? I bought the exact same one I had previosu to the Focus Pro

Dale

Rounds is Rounds

Honeywell makes a programable stat for steam, you can set to one cycle per hour. I'm not sure the number but post for Bill from Honeywell and he'll tell you. As to your round comment did you get another t86 for powerpiles or did you get a t87f? You need a t86 and it sounds like you had it wired for the fixed heat anticipator choice which works pretty well. Check the number on the round you got.

Jeff_17

I got the

same oone I had...the t86 for popwerpile...and wired it the same. Just does not operate the same way. Just wish I knew if it was defective...I am assumong it is.

BillW@honeywell

For Millivolt...

If you want the Round thermostat, the only one that will work is the TS86A. There are three models, The TS86A1389 is the only model with a heat anticipator, set it to match the current draw of the gas valve. Don't expect tight temperature control, these are coiled bimetal electromechanical stats, and 2 degrees either way is not unusual. What was the problem with the FocusPro? They are compatible with 750MV systems, and work very well with steam. Did you set it for 1 cycle per hour? Out of the box. they're set for 6 cycles.

jeff_34

Set it that way, but...

the therm regulated the temp sooooo well, it kicked the boiler on at 1/2 degree difference and then shut her down at set temp causing the rads to BARELY get warm leaving some rooms ice cold...especially on the third floor. My plumbing store returned my Focus Pro and gave me a new TS86a. Installed it yesterday and it works very well once again!

THANKS