VisionPRO 8000 for BillW@ Honeywell

David Nadle

Susan, I have a similar setup and I've noticed the same thing. I think it happens during autumn daylight hours where the sun and cloud motion combine to cause short term fluctuations in the solar heating of the house and play tricks on the thermostat.

I have not seen the 2° issue.

SusanC

VisionPRO 8000 for BillW@Honeywell

I have a VisionPRO TH8110U1003 on a one-pipe steam system and am pretty well happy with it. I do have a question about something it does (understandably more in warmer weather): When at the set T it calls for heat because the temperature must have gone down a fraction of a degree, the boiler may go on and then the thermostat stops the burner before any radiator gets any heat - only the connector to the main where the main vent is gets warm. Why is the thermostat satisfied with no heat entering the room whatsoever? In colder weather anything from a few radiators to all radiators get warm, depending upon outside T. The thermostat is set to 1 cph and in general works well.

Another weird thing about this thermostat (and another I had that was the same model) is that, when the T is going up or down, the display tends to go in 2° jumps, which seems strange for such a sensitive thermostat. It works OK when doing that so it isn't a problem - just seems strange to me.

World Plumber

The electronic t-stats operate on a 1/2 degree change. When I use them in these applications. I install a delay on break timer on the line to the boiler. This keeps the boiler running a little longer and raises the temp a fraction above the set temeperature. It stops the short cycling and conserves on fuel.
Mark

Ken Field

Other settings

in the setup are for more or less aggressive temperature control. Explore the workings of those settings and it may help. I think they are up in the 500's in the setup.

Ken F.

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Unknown

It's been a while since I've adjusted one. I know there is a code setting for steam, hot water, ect.. You may have to call honeywell themselves to make sure you have the right settings programmed in. I've done it before for a steam system 2 years ago & that seemed to do the trick. The t-stat has to know what type of heat you have.

SusanC

Would greatly appreciate a word from BillW@Honeywell

Thanks everyone for suggestions; hope for even more.

The setting for steam is #1, which gives 1 cph and that is the way my thermostat is set.

It seems that somehow radiant heat (which is one of the factors operating in this model thermostat)says the 1/2° somehow has been reached without any radiator warming. Thermostat works as expected in cold weather. In warm weather would sheer workings of the thermostat somehow increase radiant heat - seems very unlikely. Maybe it's the sun/cloud motion suggested by David although my thermostat never is hit by sun.

Unknown

Hi Susan.

I'm no longer affiliated with Honeywell, but I still will attempt to help you. First, what the others said is right. The stat is very sensitive,and is accurate within +-1 degree. Steam systems take a while to heat up and release their heat. The stat may call for heat, fire the boiler, but the boiler may not reach the pressure needed to push steam to the radiators before solar gain or other heat sources warm the room above the set point. This is fairly common during the shoulder seasons, when cool mornings become warm afternoons. You can go to www.customer.honeywell.com, and follow the prompts for a technical sheet, or for more info. The stat should be set to 1 cycle per hour for steam; out of the box, they are factory pre-set for 6 cycles per hour for forced air. The info needed to change the settings is on the tech sheet, or in the owner's manual.

SusanC

Bill Wolfe-Thanks, and...

Thanks very much for your response. It's good to know the reason for things. The thermostat does a generally good job with my steam system. It has always been set to the 1 CPH (changed to it upon installation). I made sure of that and it works well on that basis.

While we're concerned with non-essential things, did you ever notice or receive reports in your Honeywell days that the displays on these thermostats sometimes jump 2°? This appears not to interfere with proper function (e.g. doesn't cause sudden heating stops or starts). It just seems strange that such a sensitive thermostat sometimes registers with less sensitivity on the display. I would think this was this individual thermostat except that the other one I had (same model) did the same thing and in a slightly different location.