HONEYWELL VISION PRO 8000 SERIES---SHORT CYCLING

Rongold

Hi all,

About 10 years ago, I installed a Honeywell TH8110U1003 thermostat on my bedroom level, and from day 1 it short cycles the oil burner. I was working back then, but now I'm retired and home most of the time, and it drives me nuts. The colder it gets outside (especially at night) the worse it gets. The cycles are so short, the hot water baseboards on my bedroom level just barely get luke warm. The burner and circulator come on for maybe 30 seconds and then the thermostat stops calling for heat. This goes on all night---30 seconds on and 15 minutes off. The only way to stop the short cycling is to raise the thermostat setpoint, and then it cycles normally until it reaches the setpoint, and then it starts to short cycle again. I keep a spare stat, and I swapped them, but the spare stat does exactly the same thing. I also have 2 zones with old T87F thermostats, and if this happens with them, I would adjust the heat anticipator which solves the problem, but these 8000's don't have a heat anticipator. I looked through the manual, and it says something like, "If you are getting short burner cycles, call tech support". None of the adjustable parameters on this stat have anything to do with short cycling or heat anticipation as far as I can see.

So, today I called tech support and a woman answers the call, but she had no idea what I was talking about and she also said that 8000 series thermostats are obsolete and she can't help me. All 3 of my stats control Taco 272 zone valves with RP power heads and there are only 2 wires to each stat---no zone valve controller---very simple system. I checked all 3 heads, and they all draw between .98 and 1.03 amps, and the one connected to the 8000 is the one that draws the lowest, .98 amps. Is there a "hidden" heat anticipator or "hidden" function to compensate for short cycling ??? My T87F's run fine with these zone valves---There's no reason that the 8000 series shouldn't.

What has your experience been with these electronic thermostats ???

Thanks for your help.

RON

flat_twin

I have the same Honeywell Vision Pro 8000 tstat. In the installer setup menu there Cycles Per Hour settings. That may be the problem with your short cycling. See pages 15-16.https://customer.honeywell.com/resources/techlit/TechLitDocuments/68-0000s/68-0280.pdf

Rongold

flat_twin said:

I have the same Honeywell Vision Pro 8000 tstat. In the installer setup menu there Cycles Per Hour settings. That may be the problem with your short cycling. See pages 15-16.https://customer.honeywell.com/resources/techlit/TechLitDocuments/68-0000s/68-0280.pdf

I know about that setting. I have it set for 4, and the burner comes on every 15 minutes, stays on for about 30 seconds, and the baseboards barely get luke warm. The bedroom level has no baseboard in the hallway where the tstat is located. I have even tried closing all 3 bedroom doors and the bathroom door, so no heat gets into the hallway, and the same thing occurs---30 seconds of burner time and 15 minutes of off time, and repeats itself all night.

RON

SuperTech

I would try to set the cycles per hour at one and see how it goes.  If the indoor temperature is reaching the setpoint why does it matter how hot baseboards are? Maybe you have too much baseboard and you don't need really hot water to heat that zone sufficiently? Maybe the thermostat is in a bad location? You can add remote sensors to the 8000 and the thermostat will heat to a target temperature that will be an average between what the thermostat senses and the remote sensors read.

ratio

If the thermostat stays at setpoint, it's working right, as far as it knows. Is the house cold? It sounds like the heat loss of the house is a lot less than the heat system output, that the warm baseboard is enough to keep the thermostat satisfied. If the rest of the house is cool, just add a remote sensor in the coldest location (or move the thermostat). Current Honeywell RedLINK thermostats can use a wireless indoor sensor, very easy to install.

You need to widen the deadband between the cut-in & cut-out. You have the old green screen 8000 model? I'm not sure if it can be done with that one, but here's a comprehensive manual for the current, white screen, model. It might give you some insight on adjusting yours.