Honeywell Digital round Thermstats

Jim_27

Need some help out there.....

A friend has purchased a couple of the new Honeywell round Digital Thermstats T8775A1009 for heating only. He has six zones in his house and these are zoned by Zone valves. The problem he is running into is that the only time the Tstats are live is when the circulator is running. In another worlds is that the only time he can adjust the heat up/down and the display is active is when the circ is running. 2 zones have the New Digital Tstats and the other 4 are still using T87F Tstats. Any thoughts on this?

Thanks in advance for the help

Jim

Al Letellier

digital T87

From your description, it sounds like a wiring fault. How are they wired? Something is killing the 24V power. Almost sounds like they powered the transformer off the circulator connection.....anyone that doesn't use a zone valve relay controller like the Taco ZV's is asking for trouble. They are so easy to use,even a plumber can figure them out...I know that because I are one!!!
Those digitals have dip swithces in the back of the stat. Are they set right?

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John Mills_5

Power stealing

Sounds like a power stealing stat that won't work in this particular installation. Probably will need something like the White-Rodgers 1F86-244 which is battery operated and will work on anything. We haven't used this stat nor have much hydronic but that's what it sounds like.

Ted Laythe

Honeywell T8775

http://content.honeywell.com/yourhome/ptcthermostats/T8775.htm


they come with a resistor in the box that needs to be used in some applications.

Hope this helps

TED

BillW@honeywell

The T8775 is...

Power-stealing. If there is no power to the heat circuit in the off cycle, it won't work. The resistor is for use with Taco valves, to prevent display blanking when they open, but won't help in this case. The best solution is to return the T8775's and replace them with FocusPros, which are battery powered, and in the same price range.

Jeff_63

Digital Tstat T8775

I have digital T8775 Heat and cool tstat, worked fine for separate cooling unit. Started heat and remembered to put the resistor on the Taco zone head. Tstat works fine for a call for heat, stand-by time it loses power comes back on loses power comes back on. Any time Tstat is satisfied for both heat and cool it loses power and blinks display and light.

Anyone run into this that can help????

Jeff_63

Digital Tstat T8775

I have digital T8775 Heat and cool tstat, worked fine for separate cooling unit. Started heat and remembered to put the resistor on the Taco zone head. Tstat works fine for a call for heat, stand-by time it loses power comes back on loses power comes back on. Any time Tstat is satisfied for both heat and cool it loses power and blinks display and light.

Anyone run into this that can help????