Need a new type of wall stat

[colin44]

I have a drayton dial type wall stat (240VAC) in the livingroom set at 70 deg F to control my gas combi boiler for the whole house. The stat has a fixed 'cut back in' at 2 deg F below the dial setting to give a near constant temperature. This makes the boiler cycle around 3 to 4 times an hour, on and off.

This has worked fine for years, but now my neighbour is in hospital and will be during the winter, and now the diving wall (semi-detached house) is frozen, plus with the very windy drafty winter, has caused the living room to lose heat a lot faster than it used to, and the boiler is now cycling around 6 to 7 times an hour, and thus I think its wearing it out with all this firing up and closing back down repeatdly all the time.

What i need is a more course wall stat controller (adjustable upper and lower temp limits) that will switch off at 70 deg F and back on at 65 deg, so that it will cycle less (on and off per hour). I do not mind having a more variable temp, as long as it lowers the cycling by staying on longer, and off longer.

Can anyone tell me make/model of a wall stat (it can be LED style,240VAC) that would do this, as I can no longer stand all this cycling.

Thanks, Colin.

 

[TBServices]

Honeywell dt90e should be okay, although its not 240 so you'll have to do away with neutral.

 

[colin44]

Hi, I have looked at the Honeywell dt909e operation manual, and I see 'Set temperature adjustment' section, Its hard to read from the diagram if it gives the two temp setpoints, upper off and lower on?

I just want to make sure before I buy it that it does switch off at 70F (20C) and back on at 65C (18.3C), thanks.

 

[colin44]

Hi, TB Services, I have looked at the Honeywell dt909e operation manual, and I see 'Set temperature adjustment' section, Its hard to read from the diagram if it gives the two temp setpoints, upper off and lower on?

I just want to make sure before I buy it that it can be adjusted to switch off at 70F (20C) and back on at 65C (18.3C), thanks.

Also from your experience, do the two batteries powering the stat/relay last quite a while?

 

[doitmyself]

my neighbour is in hospital and will be during the winter, and now the dividing wall (semi-detached house) is frozen, plus with the very windy drafty winter, has caused the living room to lose heat a lot faster than it used to, and the boiler is now cycling around 6 to 7 times an hour, and thus I think its wearing it out with all this firing up and closing back down repeatedly all the time.

You are worrying unnecessarily. A boiler is not like a car, which will wear out faster if used only for short trips as it never gets up to a working temperature.

Modern stats are designed to maintain the temperature within very close limits (0.5C) and do this by turning the boiler on and off several times each hour.

I do not know of a stat which has an adjustable differential. The DT90E doesn't have this facility and may be worse than your existing stat.

 

[dancinplumba]

what boiler have you got ?

 

[colin44]

Modern stats are designed to maintain the temperature within very close limits (0.5C) and do this by turning the boiler on and off several times each hour.

Thanks Doityourself, but the stat is banging the boiler in 6 or 7 times an hour which is far too much for my liking, so there must be a stat out there that does what I am looking for. 70F off and 65F on.

So thank for your info, but really need 'wider limits', to control the amount of times the boiler is coming in per hour,as its doing my head in.

So I am back to asking does anyone know of a wall stat that will do this?, thanks.

Dancplumba The boiler is an Ariston comiboiler, where I myself have put the wall stat contact in series with the start circuit.

 

[dancinplumba]

reduce temp on boiler, or get new one that accepts modulating controls and save money

 

[doitmyself]

The boiler is an Ariston combi boiler

Which exact model?

 

[TBServices]

I bet the stat is in wrong room with a TRV

 

[colin44]

Model is Ariston Eurocombi SX20 MFFICE, and has been working perfectly for years with the Drayton wall stat in livingroom. Its just because livingroom is now losing heat quicker this year, that is causing the large increase in boiler starts per hour.

 

[TBServices]

Model is Ariston Eurocombi SX20 MFFICE, and has been working perfectly for years with the Drayton wall stat in livingroom. Its just because livingroom is now losing heat quicker this year, that is causing the large increase in boiler starts per hour.

Ah yes.... Forgot what thread I was reading.

 

[doitmyself]

The boiler is an Ariston comiboiler, where I myself have put the wall stat contact in series with the start circuit.

Do you mean that it is in the 230V supply to the boiler? If so, this is wrong; the boiler needs a permanent supply. There are terminals within the boiler for connecting a thermostat and/or a timer.

 

[colin44]

This problem is not boiler wiring related, it is wired up properly, and has been since instal.

The boiler needs a permanent supply. YES CORRECT

There are terminals within the boiler for connecting a thermostat and/or a timer. YES CORRECT, I used them as per the wiring diagram supplied at the time.


Please note I want answers to a replacment wall stat, not boiler questions, there is nothing wrong with the boiler.

If you cannot answer about a stat on the market that will switch off at 70F and back on at 65F, then there is no need for you to reply further, Thanks.

 

[Bagsy]

If you are prepared to invest, the Dataterm will be a good product I have used these for years, they were the first to have optimum start way before the big heating control companies. Savings between 18% - 36% compared with conventional controls. They are still in business and all made in the UK Intelligent Central Heating Controls - Save money on heating bills

 

[doitmyself]

If you are prepared to invest, the Dataterm will be a good product I have used these for years, they were the first to have optimum start way before the big heating control companies. Savings between 18% - 36% compared with conventional controls. They are still in business and all made in the UK Intelligent Central Heating Controls - Save money on heating bills

But they provide 'close temperature control', which the OP does NOT want!

 

[DirksPlumbing]

Honeywell CM901, CM907, CM921, CM927 can be adjusted and as well limited in the number of switching cycles if required. But indeed I do not see any danger in the number of cycles.
The beautiful microbore systems would then wear a boiler in a very short time as these tend to struggle to get rid of the energy quick enough resulting in a huge number of on/off cycles.

 

[Bagsy]

The Dataterm is enormously vast, there is no reason that you cannot set it to achieve anything you want. It will take individual plans with ease, is user friendly and in my experience one of the best controls out there (not to be confused with a programmable room stat). It is a computer with a complete learning curve, so will adapt exactly to what you want from it. They were also the first controller with a GC number & that does not come cheap, now recommended by the energy saving trust. I accept that this unit is not for everyone and cost will be a factor. But pound for pound, I have to be convinced of something better. It has true optimization rather than pre set time cycles linked to temperature compared with some. It has a fuel monitor and you can plug the laptop in to help search for any diagnostics on the system. Good product and will achieve total comfort in the customers home. It is my belief that there is not another product directly competing with Dataterm, as most have gone about things in a different way. Whatever you chose, it will be better than a standard control system for sure. There are lot's of good products out there & I fit many different types, I have been fitting Dataterm in it's various guises since the 1990's. When you can cut an annual fuel bill for a customer in half, by boiler change and controller change, this was enough to convince me with total comfort for the customer. My advice is to give Gary Belgiem a call at Warmworld & talk to him. He is a heating engineer by profession himself, not a salesman. He talks good sense and will answer any questions you have competently. Better than I can, I may add

 

[colin44]

Honeywell CM901, CM907, CM921, CM927 can be adjusted and as well limited in the number of switching cycles if required. But indeed I do not see any danger in the number of cycles.
The beautiful microbore systems would then wear a boiler in a very short time as these tend to struggle to get rid of the energy quick enough resulting in a huge number of on/off cycles.

Hi Dirksplumbing, I have read the PDF manual for these and I can easily see the setting of the upper setting at 70F off, but still cannot find adjustment for the lower setting at 65F on.

Can you explain how it does that from the manual, so I can set the above to get the boiler cycles per hour down (ie, the boiler runs longer and stays off longer). Thanks.

EXPERIMENT
I did an experiment yesterday and ran the boiler manually (not temp stat controlled) for 15 minutes on and 15 minutes off, then repeated this for a few hours (that's about two boiler cycles per hour) and there was a remarkable difference to the house, as the radiators being on longer came up to real temperature, and held their heat longer, the downstairs living room reached 72.4 F and after 15 minutes off went down to 68 F, upstairs was warmer for the first time in ages, up at least 5 F more than usual, so the problem is just getting the boiler to remain on for some time via a temp stat, and then off for a while, at the moment its staying on for 5 minutes max and going off for 5 minutes max in temp stat control (6 boiler cycles per hour), so the radiators are not having time to hold their right heat, which is crazy, so an upper and lower limit stat is the answer, which will do this, and lower the boiler cycles, which would be the answer to my problem.

 

[tamz]

Pull the neutral out of the stat you already have and it will react slower or buy a few sheets of this Gyproc ThermaLine SUPER and line the walls.
Get real ffs. There are ways to do this not stat related but i'll let you search the interweb for an answer since you know what you are looking for.

 

[doitmyself]

The Honeywell CM9XX programmable stats have two adjustable System Parameters which might help.

Parameter 1:Ot sets the minimum ON time, which can be from 1 to 5 Minutes.
Parameter 2:Cr sets the cycle rate - 3, 6 or 12 cycles per hour

Setting 1:Ot to 5 and 2:Cr to 3 should help reduce the problem.

 

[petercj]

Another way around the problem could be to fit a wireless stat and leave it in a room that has a more stable temperature.

Either way, I think you will need to break out the thermals and extra socks to insulate against the temperature drop, which is likely to be quite noticeable.

The real problem is the lack of insulation in the room and not the stat, and in the longer-term it might be a better investment to look at ways of insulating the room than to spend out on a more complicated temperature control system that is a "sticking plaster" approach to the problem.

If you are handy, you may well be able to dry-line some of the colder walls at a lesser cost than fitting a fancy temperature control system that might not be as reliable as a simple old fashioned room-stat. Internal glazing is within the scope of the average DIY'er, and heavyweight lined curtains can make quite a different during winter evenings. A door closer costs around 10 pounds and is one of the best energy saving investments around.

Regardless of how often your boiler cuts in and out, you are still losing money by letting the heat escape.

 

[DirksPlumbing]

Hi Dirksplumbing, I have read the PDF manual for these and I can easily see the setting of the upper setting at 70F off, but still cannot find adjustment for the lower setting at 65F on.

Can you explain how it does that from the manual, so I can set the above to get the boiler cycles per hour down (ie, the boiler runs longer and stays off longer). Thanks.

It is the proportional bandwidth parameter. But bear in mind that more than 3 degC would potentially cause draft effects often described as cold radiation.
The Honeywells would not allow to overdo this anyway but if you are fiddeling you might even worsen the problem.