DIY Doctor UK DIY Forums

I've just had a new Vokera Syntesi25e combi condensing boiler system fitted.The company also fitted a thermostat in our hall where the only radiator without a TRV is located.

The problem I've got is that the boiler is not constant. The boiler fires up and raises the temp well above the setting on the thermostat, and then doesot come back on until the temp drops back. It may seem odd but the difference is noticable and seems to get coldish.

I would have thought there would be a way of setting it, to be more constant i.e. stable temp.

The thermostat has been replaced already ( Danfoss manual model ).

The boiler has a manual timeswitch and now the thermostat only works with the boiler set to "on", with the the timer nodules on also. I'm sure that on the original thermostat, the thermostat worked without the above required??

I've got the boiler set to Water/Heating with both dials turned to about 3/4 full.

Can anyone please help with this one. It is driving me nuts

When I first had gas central heating installed, I left the original Economy 7 thermostat in use. Eventually problems arose, and I took the Honeywell thermostat to our local electrical factors to get a replacement. The staff immediately saw that the model of thermostat required (Sunvic equivalent), was fitted with small resistive heater below the bi-metallic strip/switch;-- otherwise it was virtually a copy of the E7 version. This local heater acts in the same way as the heaters in cooker simmerstats;- it switches off the radiators a mite earlier than without it, then cools quickly, and powers-up the radiators again----rapid cycling. Look inside your outer cover of the thermostat casing to make sure there is a small resistor below the switch, where it will boost the temp. of the up-flow of room air thro' the unit.