Choice of thermostat advice please

[diselsamm]

Thank you gmartline! I will discuss this with my heating engineer and see with him into heat loss calcs and choosing one of these keys.

 

[Chuck]

Looking at the Honeywell Y6630D1007 datasheet, it has a minimum on time of one minute and a cycle rate of six cycles per hour. These are factory set and can't be changed. It doesn't have a setpoint hysteresis band because the time delays have a similar effect.

In addition, the boiler has its own anti-short-cycling behaviour. This is proprietary but is something like "If the boiler has cycled more than twice in the last ten minutes wait ten minutes before firing again." (This is from memory, I don't have my notebook to hand.) I think your boiler has an 'Info' button you can push to make it display its status so you can keep an eye on what's happening.

 

[gmartine]

No such thing on that regular boiler Chuck, only two control knobs and a LED.

 

[Chuck]

No such thing on that regular boiler Chuck, only two control knobs and a LED.

Good catch, thanks. I missed the 'R' on the model number. OP should forget what I said about the boiler behaviour, I don't think it's applicable to that model.

 

[diselsamm]

Gmartline, my current circulation pump is a Grundfos UPS3 15-50/65, which replaced the standard red-coloured Grundfos pump.
The current one is set at constant speed 1. The pump got other speeds as well. What speed mode and speed would you use?
I do not have a UFH and previously the system was with a F&E tank, now pressurised with indirect vented solar cylinder and expansion vessel.

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[gmartine]

Lowest possible speed as long as radiators get up to temp and you have enough flow rate so setting 1 should normally be fine. You do have to set the pump curve on those, proportional or constant pressure depending on your system.

One other thing relating to your original enquiry, the stat really shouldn't be short cycling as much as it is. Just make sure it's correctly postioned out of draughts and high enough and the connecting corridor is warm enough or keep the door closed or it will be susceptible to the behaviour you describe.

 

[diselsamm]

Lowest possible speed as long as radiators get up to temp and you have enough flow rate so setting 1 should normally be fine. You do have to set the pump curve on those, proportional or constant pressure depending on your system.

One other thing relating to your original enquiry, the stat really shouldn't be short cycling as much as it is. Just make sure it's correctly postioned out of draughts and high enough and the connecting corridor is warm enough or keep the door closed or it will be susceptible to the behaviour you describe.

Thank you Gmartline. The pump is not that model where you can set the curve per se, but can define the mode and speed, if I understand correctly.

As to the thermostat I do suspect it is malfunctioning as the place it is sat on is the living room, on a shelve, about 1.2m above the floor. No draughts, and temp is stable between 18 and 19C with this weather and heating setting. Funny though my thermostat is sat at 17C but the room temp is 1-2C higher.

How these code keys operate? Is it similar to the way the remapping on a car operates? I assume once my heating engineer puts on a smaller output one, he will also have to make adjustments to the burning mxing rates, etc? I will have a conversation with him about this next week.

 

[gmartine]

By curve I meant mode.

No other adjustments required except to swap out the key code, just make sure to label the boiIer with it's new rating.

The different keycode vary in resistance only so I guess that pulls down a particular voltage which triggers the respective "map".

The whole ri range is so simple it's the same boiler from 9 to 24kw cept the key code.

 

[diselsamm]

Update:
So I had the plug replaced and the boiler is "detuned" to 12kW. My impressions: very positive. The boiler is much quieter. And the cycling issue is in my opinion gone. Thank you gmartline!

I would like to replace my current thermostat and need your recommendation please.

I currently have

• Honeywell Y6630D1007 Wireless Analogue Room Thermostat
• Honeywell ST699 2-channel programmer.

and I think I would like to keep the programmer and replace the thermostat and its receiver. I am thinking to replace them with Y87RF2024. What are your thought? Thanks!

 

[diselsamm]

Update:
So I had the plug replaced and the boiler is "detuned" to 12kW. My impressions: very positive. The boiler is much quieter. And the cycling issue is in my opinion gone. Thank you gmartline!

I would like to replace my current thermostat and need your recommendation please.

I currently have

• Honeywell Y6630D1007 Wireless Analogue Room Thermostat
• Honeywell ST699 2-channel programmer.

and I think I would like to keep the programmer and replace the thermostat and its receiver. I am thinking to replace them with Y87RF2024. What are your thought? Thanks!

spoke too early, the cycling issue is not resolved. So focusing now on the the replacement of the thermostat