Better programmable stat..

[D_Hailsham]

I assume you bought a brand new one and have the Installation Instructions.

You could try increasing the Minimum On Time parameter (1:Ot). It will be set to the default, one minute. See section 4.1 on page 7 then section 4.5.2 on page 10. Try changing it in 1 minute steps and give it time to learn!

Is Optimization (8:OP, para 4.5.1) turned off? If so, turn it on. Then set the times to when you want the required temperature to be achieved, e.g when you get up in the morning. The programmer will automatically work out how much earlier the boiler needs to come on, depending on how cold it is.

 

[D_Hailsham]

TPI is at odds with what you want from a condensing boiler IMO. Long burn, no cycling at as low a flow temperature as you can. TPI is switching it on and off all the time, fine on a non-condensing boiler I suppose.

Strange then that all Honeywell's current digital stats have TPI as standard - even the top-of-the-range Evohome system. Presumably Honeywell never test their equipment with condensing boilers.

TPI does not switch the boiler on and off all the time, even though the six cycles per hour and one minute minimum do suggest that. The cycle time set in the stat is just a starting point. The stat learns how often and for how long the boiler needs to run in order to maintain the set temperature. This obviously depends on the rate of heat loss.

Have a look at Honeywell CM900 Series, which is a Powerpoint Presentation, produced when the stats first came out in 2005.

 

[wipeoutdude]

I assume you bought a brand new one and have the Installation Instructions.

You could try increasing the Minimum On Time parameter (1:Ot). It will be set to the default, one minute. See section 4.1 on page 7 then section 4.5.2 on page 10. Try changing it in 1 minute steps and give it time to learn!

Is Optimization (8:OP, para 4.5.1) turned off? If so, turn it on. Then set the times to when you want the required temperature to be achieved, e.g when you get up in the morning. The programmer will automatically work out how much earlier the boiler needs to come on, depending on how cold it is.

Yes, a new on and I have all the instructions.. I will see how it behaves this evening and then see if increasing the minimum on time is what's needed..

I decided to leave optimisation off for now and have set the program to be exactly the same as my previous stat so I can try and gauge any change in gas usage.. Once I get to see how it operates I can adjust the program and start using optimisation as well and will see what effect that has on gas usage too..

I looked in the boiler manual to see if there was a way to speed up the ramp up of the boiler but there doesn't seem to be.. There was a setting 2.3b "Anti fast cycle time" which was set to 10 min by default that I have changed to 5 min based on the fact the stat is probably going to call for heat again within a 10 min period because it's set on 6 cycles per hour (10 min)..