2 weeks ago installed new grant vortex condensing oil boiler. Great it heats house up very quickly but since I only have a horstmann basic programmer 425 diadem - decided to install a room thermostat to control heating better. Purchased and fitted cm927 but the house warms up very slowly. Thermostat is in hall with target temperature of 18. The last 3 days temperature reads 15 when heating comes on and it is taking 2 1/2 hours to reach 18. Previously without stat this was reached in 30-40 minutes. I am working the stat on manual it was my belief that boiler would stay on still targeted temperature was reached or close to it. Default setting was for a gas boiler but I have changed this to oil burner. Burn time 4 minutes and cycle 3 times an hour. Would be grateful for any advice as to why stat is so slow.
Honeywell cm927 room thermostat
- Thread starter liam2308
- Start date
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That terrible word "wireless" comes to mind!!
The room stat may be at fault by not remaining closed until desired temperature is reached. Your burner should keep going until it reaches the desired temperature.
If its the only thing you have changed, then obviously its the first thing to doubt!
They are only £15 if wired?
The room stat may be at fault by not remaining closed until desired temperature is reached. Your burner should keep going until it reaches the desired temperature.
If its the only thing you have changed, then obviously its the first thing to doubt!
They are only £15 if wired?
How long have you had the stat? Is the temperature dropping to 15 because that is the night time setting, or do you have a well insulated house?
Manual just means that you have a fixed temperature for the whole time, instead of varying time temperature settings over the 24 hours. I assume you turn the heating to a lower temperature at night and then turn it on when you get up. That means you are not taking advantage of the optimization feature. With this you set your get-up time and temperature as setting 1 and the programmer brings the boiler on in time for the house to be up to the correct temperature when you get up. When the boiler turns on will vary according to how much the house has cooled down overnight. It takes the stat several days to learn the cooling characteristics of the house.
If you don't need several time/temperature settings during the day, you can always set 1 to get up temperature and 6 to night time temperature and disable the rest.
Started to ask about that and then I read the above.
PS Forgot to ask: How is your hot water heated -cylinder or combi
Many thanks for prompt replies . House is well insulated 270mm in loft - double glazing - approx 14 years old. I am using diadem to bring on power/electric at 4.00 afternoon - obviously 927 stat then takes control we arrive in at appox 5.30 temperature reading 15 - target is 18 at approx 7.30 it reaches 17.5/18 also the burner signal on stat is on all the time. But on checking in garage where boiler is - green light is coming on receiver box but the boiler is definitely not coming on for long enough. I wanted to test the stat on manual first before I set up full automatic and leave the power on the diadem 425 on all the time. House is approx 1400 sq.ft. Boiler is rated at 26 At present diadem is programmed for 5.30 in the morning - off at 7.30 am. as we go to work. It comes on at 4.00 afternoon and goes of at 11.00 pm. Stat is only 2 weeks old. Even though comes on for 2 hours in morning reading this week 15.5 it does not reach 18 by the time we go out. PS boiler stat is set at maximum. !!!!! After some more checking I have found that green is on receiver calling for boiler but boiler is not on. On checking power going to boiler which is live - the problem seems to be settings in the boiler which are not bringing it on. I will have to check this out with supplier - it looks as though the CM927 is working correctly.
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If you have connected the CM927 relay box to the original thermostat wiring, the L terminal will be connected at the other end to the CH ON terminal of the timer.
The CM927 relay box needs a permanent supply, so CH has to be set to continuous on the old timer. There is a danger that someone will fiddle with the old timer, so I prefer to move the wire from CH ON to the L terminal of the old timer.
Totally agree with you. I am now certain my problem is the boiler - as it is only 2/3 weeks old. I will get installer to check stat settings on the boiler and contact makers Grant for advice. Again many thanks for your time and advice
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