Choice of thermostat advice please

diselsamm · Oct 22, 2023

Hi

I'm having issues with my wireless Honeywell thermostat. It's sat in the living room, set at 18C currently. It makes my Worcester Greenstar 18Ri to short cycle. So, the moment it gets cold outside my boiler works for about a minute, then stops, and starts again in about 5 minutes, then repeat. Obviously the temp in my living room does not fluctuate so much. I've got a total of 8 radiators at home up and downstairs, and happy to agree the boiler is oversized for my property. But I can clearly see the thermostat is the one calling for heat (know this from the led light on the receiver).

I've been thinking of having the thermostat and receiver replaced with maybe a Drayton Wiser or Greenstar Comfort I. Any suggestions on the choice of thermostat?

I've a Honeywell Y6630D1007 wireless thermostat and a Honeywell ST699 programmer and want to rip them off.

diselsamm · Nov 19, 2023

Here is the long story. I inherited a system with a F&E tank, which was noisy. We converted the system to a sealed one. But it was not properly cleaned. In the mean time the HWC failed as well. My trusted heating engineer (not involved in any of this previously) cleaned the system chemically and flushed (both chemically and with a pump) the boiler heat exchanger as was very sludged due to previous owner neglect and following sealing of the system. We discovered that the boiler was overheating and was not going over 68C (locking out). The location of the magna clean filter was initially wrong and that was rectified. Currently the system is clean, the boiler finally dropped gas consumption, the plug you suggested had a further positive impact. It is nice and warm at home now. The system is properly balanced with temp clamps. The boiler is properly condensing. In fact the radiators are not hot to touch. Which is different to how they used to be, and still it is much warmer and nicer temperature wise at home.

diselsamm · Nov 22, 2023

I wanted to bring this one to conclusion. My cycling issue is completely eradicated. What solved it was: 1) plug key, kindly suggested by gmartline (thank you!) and 2) replacement of the wireless thermostat and receiver with a new (digital) one. I chose
Honeywell Home Single Zone Thermostat (Y87RF2024). The replacement was super easy and took less than 5 min.
I will make a new post asking for advise on how to decommission the wired programmer.