Thank you so much to all who have contributed with suggestions. The Honeywell CM 907 sounds ideal but just one quick question. Do the up and down buttons on the front allow you to quickly increase the temperature. If we come in and the house seems a bit chilly, my wife just turns the dial on the existing thermostat to increase the temp. Is it just as easy to do this on the CM907. Thanks again for all the help, Lawrie
Unfortunately, yes, it will be just as easy for her to do that... ;-)
Once you've manually adjusted the set temperature like that it'll remain so until the next set point. An alternative strategy is to press the 'Party' button which will allow you to set the temperature for x hours.
Mathew
No, some require the hot water to be on if the central heating is on, - possibly earlier models aimed a gravity hot water systems.
I have had a TP9 which was an earlier model. I rarely touch it, and it provides accurate temperature control.
Michael Chare :
Isn't that a feature of the plumbing rather than the controller?
Anyway the point is that you don't by any stretch of the imagination need two controllers in order to have independent timing for CH and HW. And I'd prefer to have just one controller, as I do now, but with the extra features of a modern programmable thermostat.
Not necessarily! My Randall SET5 can control both (although I now only use it for HW, with CH on 'constant') but it only has one timer, with 3 on/off periods per day. You can independently set HW and CH to ON, OFF, or Timed - but you *can't* set them both to Timed and have them come on at *different* times.
But, by using the SET5 to time the HW and the Honeywell programmable stat to time the CH, I can make them *completely* independent of each other.
That's not quite the same thing! Systems with gravity HW and pumped CH use the HW side to turn the boiler on and the CH side to turn the pump on - and don't let you have CH on its own because you'd just be pumping cold water round the system. But that's not what I was saying.
I was saying that if a programmer has only one *timer* - as many do - if both HW and CH are set to Timed, they both have to be on at the *same* time. [But if the system is fully pumped, you can still switch it to have just CH with no HW if you wish - unlike a gravity system].
Right, thanks.
It's amazing how quickly one forgets the bad (technologically speaking) old days.
Yes, but as someone else has said, it will revert to the normal programme at the next scheduled switching time - unlike a manual stat, which stays put until you twiddle it again.
Someone else has mentioned Party Mode - which is a useful function. It allows you to depart from the set programme for a specified number of hours. Whilst its primary use is to keep the house warmer for longer - like when you're having a party - you can also use it to make the house cooler. So, if you're going out for 4 hours, use it to turn down the heating for 3 hours, and it will be warm again by the time you return.
Some programmable stats also have a Holiday Mode - which enables you to effectively turn the heating off for up to 99 days, but have it come on again on the day you return - or maybe the day before. It will still act as a frost stat while you're away, and turn the heating on if it gets
*really* cold - like less than 5 degrees.
That was one of the first things that I swapped at my brothers house. I installed a proper programmer where the HW and CH had independent time controls.
It is a fully pumped system, and now the timed sections with the HW and CH are not linked.
Well, it was quite advanced in its day (about 1990) - being electronic, with an LCD display. However, gravity HW systems were still quite common at that time (although mine was fully pumped) so I guess that no-one had really thought about wanting to time HW and CH independently. Anyway, it was a significant advance on the normal Sangamo-Weston-type mechanical clock used previously.
Well, actually you do. It's just that your two controllers live in the same box and share some of the user interface. :-)
With the Honeywell you can program the maximum set point. It's normally
35degC but mine is set to 23. If you want to be a right git then set it to 21 and the other 'arf will need to lump it.I have the CM907 and it gets 10/10 for usability but it does bother me that it was designed to deliberately cycle the boiler on and off at between 3 and 12 times per hour (default 6 for gas boilers). I don't want this as I view deliberate cycling of the boiler and controls to be a major contributor to component wear and system life reduced life.
Mine is currently set to 3 cycles per hour with a minimum on time of
5mins but it is only just getting the water loop up to temp when it switches off again. Unfortunately you can't turn this behaviour off so I'm looking for looking for a replacement but it's hard to find reasonably priced controls that look good, have the remote sense that I want and can turn off proportional control.
I had the TP7000 with remote sensor (well two actually for two separate zones) and it did not allow setting a minimum 'on' time. The sensors seemed EXTREMELY sensitive and the (oil) boiler was being switched on and off at far too frequent an interval. After a lengthy discussion with Danfoss customer support - and to be fair they tried to be helpful but with no satisfactory result - I gave up and replaced wih the Honeywells following many good reports on this group. They allow programming of a minimum 'on' time and they have been the doggies from day one. If the TP9000 is the same as the 7000 and you're using an oil boiler, I'd strongly recommend that you think twice. HTH
Please reply to group - email address is not monitored Ian
Nice tip. Cheers.
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