Combi boiler issues?

MrTrav15

Hi Everyone,

I have a baxi combi boiler 105e in a 3 bed detached house. I also have a British gas wireless thermostat fitted in the living room. I set my thermostat to reach 18.5 degrees in mornings and evenings. However I have noticed that even once the temp is reached (usually gets to about 18.7) the boiler still fires up almost like clockwork every 5 minutes. It stays on for a minute or two and the shuts off. It does this all night until it is programmed to turn off for the night.

I thought the whole point of a thermostat was to only fire up the boiler once the temp dropped below whatever the set temp was ie 18.5 degrees. Does anyone else's boiler fire up this often? And is this costing a fortune? Also how long should it take to warm a room up. It took 40mins today for the thermostat to go from 16.5 to 17.5.

MrTrav15

Hi thanks for the reply.

I understand the thermostats job is to keep the temp constant. I assumed the way it worked would be to heat up to set point (in this case 18.5) and then once it saw the temp drop to 18.4 it would send a signal to the boiler to turn on. What I've been getting lately is even when the temp is at 18.7 it still fires up every 5 minutes.

espresso

MrTrav15 wrote: »

Hi thanks for the reply.

I understand the thermostats job is to keep the temp constant. I assumed the way it worked would be to heat up to set point (in this case 18.5) and then once it saw the temp drop to 18.4 it would send a signal to the boiler to turn on. What I've been getting lately is even when the temp is at 18.7 it still fires up every 5 minutes.

You are correct in how your stat should work and digital stats have very little hysteresis so maintain the set temp accurately.

BG don't make stats and they are usually Drayton Digistat 2 etc. These have a setting accessible in installer mode that controls:

Intelligent Delayed Start (Energy saving feature).
The Intelligent Delayed Start is an energy saving feature which automatically reduces the warm up time for the heating system.
As the weather becomes milder, Intelligent Start will delay the heating start times so that fuel is not wasted bringing the room up to temperature earlier than necessary.
Note: Intelligent Delayed Start only applies in Auto mode.
Intelligent Delayed Start default is in OFF mode.
To switch on Intelligent Delayed Start enter the Installer Options
Menu (Refer to Installer Options 5).
Note the Intelligent Delayed start option is not suitable for Hydronic underfloor application.
Ensure Installer option 5 is set to Off before final commissioning for Hydronic underfloor application.

You may want to switch this off.

MrTrav15

Not sure if that is the make I have. The thermostat is simply called British Gas Smart Linked Thermostat so not sure those instructions mean much to this thermostat.

espresso

MrTrav15 wrote: »

Not sure if that is the make I have. The thermostat is simply called British Gas Smart Linked Thermostat so not sure those instructions mean much to this thermostat.

Your basic problem is that you have a "British Gas Smart Linked Thermostat" and you don't know how to use it e.g. change the various setting options to suit your requirements. Google is your friend but search for an installation manual not a user guide.

The OP has had his head in the sand for months and did not bother to return to his last thread re. high gas consumption here.