Thermostat not reaching the temperature which I have set.

[easybullet3]

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Honeywell CM927 Thermostat
Ethos 54C (Condensing Combination Boiler)

I set the Thermostat to 26°C (79°F). The boiler fires up and heats the home to 22.5°C (72.5°F), and then it stops.
* The thermostat shows me it is currently 22.5°C, but refuses to continue heating to 26°C.

I just can't seem to get the room temp higher than 22.5°C
Even if I set the thermostat to 28°C, or higher, it always stops at about 22.5°C


The radiators are all about 55°C to 60°C (according to my infrared thermometer)

The boiler display is hovering around 68°C. But when the flame kicks in it rises to 79°C over the next 15 seconds and then abruptly falls back to 68°C again.

At one point i pressed the INFO button on the boiler, it gave a code: t1 (which lasted for a few mins).
The manual says t1 code is "Supply temperature too high during CH demand or anti-recycle timer"

But after a few mins, the code went away and hasn't returned.
But thermostat room temp won't go above 22.5°C

Does this mean that the boiler can't handle the heat, so it cuts off at a certain temperature?
or, does it mean that something else is inefficient?

hopefully, i gave enough info.

Thank you 🙂

 

[king of pipes]

26° c is way to high even 22 °c is to warm in my opinion , how many radiators on your system ? It maybe that the pipework is undersized as you say the boiler can't loose it's heat into the pipework and radiators

 

[Deleted member 120897]

What boiler is it? System type?

 

[oz-plumber]

Most of the Honeywell thermostats have another manual for changing system parameters.

Your thermostat may have been internally programmed to only heat to 22.5C.
No matter what the requested temperature is.

I had one recently where the owner of the property rented the houses out to students.
I couldn't get the thermostat to work over 19C and could not get the boiler to fire up upon thermostat call for heat by upping temperature. The flame on the screen come on but the boiler wouldn't activate.

I rang the owner, who told me that the thermostat was programmed to go to 19C max and the time periods and temperature were locked.

It was the same thermostat, CM927, wall mounted and wired to boiler.

He was paying the gas & electricity bills for the property included in the rent.
He got his own back when the students bought electric heaters and had them running day and night.

 

[Chuck]

26° c is way to high even 22 °c is to warm in my opinion

You're not trying to grow cannabis.

 

[easybullet3]

What boiler is it? System type?

Its written in my original question (above):
Honeywell CM927 Thermostat
Ethos 54C (Condensing Combination Boiler)

 

[easybullet3]

26° c is way to high even 22 °c is to warm in my opinion , how many radiators on your system ? It maybe that the pipework is undersized as you say the boiler can't loose it's heat into the pipework and radiators

I guess everyone has their own preference.
Personally, I like it very warm at home.
my dad likes it at 22, but I always find it too cold in his home.
another friend of mine heats their home to 20, and I wear TWO thermals tshirts under my jumper in her home.
i'm fine with cold weather, but at home, I want to be completely warm and relaxed.
To be honest, 24 to 25 is ideal for me. But, i cant get this system past 22.5

it's a 2 bed flat, and there are 4 radiators and also a towel radiator in the bathroom.

 

[easybullet3]

You're not trying to grow cannabis.

Lol.
i'm afraid not.

 

[easybullet3]

Most of the Honeywell thermostats have another manual for changing system parameters.

Your thermostat may have been internally programmed to only heat to 22.5C.
No matter what the requested temperature is.

I had one recently where the owner of the property rented the houses out to students.
I couldn't get the thermostat to work over 19C and could not get the boiler to fire up upon thermostat call for heat by upping temperature. The flame on the screen come on but the boiler wouldn't activate.

I rang the owner, who told me that the thermostat was programmed to go to 19C max and the time periods and temperature were locked.

It was the same thermostat, CM927, wall mounted and wired to boiler.

He was paying the gas & electricity bills for the property included in the rent.
He got his own back when the students bought electric heaters and had them running day and night.

interesting information.
I have the thermostat here, in my hands.
So does that mean it is something which I can modify myself?
or, is the Honeywell thermostat is somehow locked and not able to be changed ?

unfortunately, I rent the property and I pay for utility bills, so i cant do the clever idea which you mentioned.

 

[Deleted member 120897]

Its written in my original question (above):
Honeywell CM927 Thermostat
Ethos 54C (Condensing Combination Boiler)

Oops, my bad, guess I should have gone to specsavers. Seems like it’s knocking off on the boiler thermostat as opposed to the room thermostat.

 

[king of pipes]

That's a big output boiler for a little flat the boiler is Dutch I believe ? and needs to be configured to suit the size of the system minimum setting is 10kw kw which is more than enough for your flat up to 38 kw it's quite a complicated unit and who ever sorts it out will need the manufacturer's instruction manual and or at least the user manual - 4 rads may well not be enough to heat your flat to the temperature you require ,the boiler cannot get rid of it's heat quick enough gets to temperature and switches off and won't switch back on until the return temperature drops enough to start the heating cycle again you'll need a engineer to sort this. Kop

 

[Chuck]

To be honest, 24 to 25 is ideal for me.

Might be worth having a chat to your doctor. I can think of a couple of treatable medical conditions that have symptoms that match what you are describing.

There is an 'upper limit' parameter that can be set for the CM927 but IIRC it is adjustable only in increments of 1°C (so it can't be at 22.5°C) and if set it won't let you ramp the displayed 'target' temp above the limit. This is not what you are describing so I think that @king of pipes (post #11) has nailed it for you.

Keep in mind that if your flat is at 25°C you are going to be pumping a significant amount of heat into your neighbours' flats. This will be nice for them but very expensive for you.

 

[easybullet3]

That's a big output boiler for a little flat the boiler is Dutch I believe ? and needs to be configured to suit the size of the system minimum setting is 10kw kw which is more than enough for your flat up to 38 kw it's quite a complicated unit and who ever sorts it out will need the manufacturer's instruction manual and or at least the user manual - 4 rads may well not be enough to heat your flat to the temperature you require ,the boiler cannot get rid of it's heat quick enough gets to temperature and switches off and won't switch back on until the return temperature drops enough to start the heating cycle again you'll need a engineer to sort this. Kop

So, if this is the case, does it mean that i am best to have ALL radiator valves fully open to aid heat loss?
Would there also be any benefit in opening up the Lockshield valves on each radiator a little bit more?
if I understood you correctly, the boiler is too big for my 4 radiator + 1 bathroom towel radiator (2 bedroom) flat. And it is overheating due to lack of heat loss.
So, if I can increase the heat loss, the boiler won't be overheating as much.
increasing heat loss = having all valves fully open.
- the theory makes complete sence 🙂
So, i'm wondering about the Lockshield valves,,, whether they help make radiators hotter also ?
if so, I will turn them all up half a twist

 

[easybullet3]

Might be worth having a chat to your doctor. I can think of a couple of treatable medical conditions that have symptoms that match what you are describing.

There is an 'upper limit' parameter that can be set for the CM927 but IIRC it is adjustable only in increments of 1°C (so it can't be at 22.5°C) and if set it won't let you ramp the displayed 'target' temp above the limit. This is not what you are describing so I think that @king of pipes (post #11) has nailed it for you.

Keep in mind that if your flat is at 25°C you are going to be pumping a significant amount of heat into your neighbours' flats. This will be nice for them but very expensive for you.

Thank you for the info about my thermostat.
I agree... the user: 'king of pipes' makes a lot of sense.
I replied to him just a few minutes ago.
you mentioned that the CM927 thermostat wont allow a person to ramp up the 'target temp' higher than the 'upper limit parameter', so yes, this does rule out my situation because I am able to set a 'target temp' right up to 35°C.
I think i can agree that 'king of pipes' may be correct 🙂

by the way: regarding my love of a heated home; its actually psychological, I think.
When I lived in Thailand for 15 years, I was happy with the climate.. even when it reached 41°C outside.
All my thai friends complained when the weather went below 20°C outside. They literally act like they are freezing.
I remember one winter it went down to 11°C outside (which is probably the lowest I can remember it ever being there). and it was very obvious that almost all thai people were suffering (coz they are not used to that sort of weather).
After returning to the UK, I think i've sort of got used to that temperature. I miss it.
Also, in my home (sorry for the mental image) I like being in my underwear and tshirt.
I dont like having to wear jeans or jumpers at home. I want to feel like its nice and warm inside the home.
if you are at home in underwear in 21°C, its bearable, but its not the same as when you are enjoying the nice warmth when you go on holiday to a hot climate.
honestly, I dont have any medical condition. My blood circulation is fine. and I even take cold showers sometimes which I can tolerate (because its only for a minute). I never take very hot showers... usually its just warm-hot... even in winter.
But around the home, I like the nice warm feeling.
Making sure my thermostat is accurate, I have 4 mini temperature devices. so, right now the room is approx 21 to 22°C, and I am ok... but I dont like it.
i know, from experience, I will be happy if it were 24°C
Prior to living in thailand, I lived in a hot area of Australia for a few years. and i always seemed to be in hot climates.

 

[king of pipes]

Even with every valve fully open you will find you have the same problem I'm guessing it may possibly be slightly better ? if the boiler is configured to its lowest setting but this needs to be done in the installer setting parameters , power output , pump speed , and gasvalve can be be adjusted this is not something you should be touching I'm afraid🙁 I doubt 4 rads and a towel rail will need a output of 10 kw , by all means open them fully but I fear you will see no improvement?. your flow temperature will match your return temperature within a short period of time so your boiler will cycle on and off as it does now. Kop

 

[Ben-gee]

I guess a solution is to increase the size of your radiators. These will have been chosen to get the rooms up to 20/21 degrees C, which they appear to do.

 

[easybullet3]

I guess a solution is to increase the size of your radiators. These will have been chosen to get the rooms up to 20/21 degrees C, which they appear to do.

I agree that an increase in radiator size will definitely help 🙂
But I would be shocked if a plumber would have made a conscious effort in choosing my current configuration of rads with a goal to reach 20°C to 21°C. It's not exactly a high expectation. It is like a sound engineer setting up a sound system in a club with a goal to get the maximum volume to 'slightly loud'.

 

[king of pipes]

It's not unusual for heating installers to fit boilers and to leave them as they were set up in the factory , during commissioning there is a section in the manufactures installation manual which should of been completed detailing what the settings are ? and the tests results were ? it is proof that has been completed and configured correctly, this is called the benchmark there are many online heating calculators online to work out the radiator sizes needed to achieve a set indoor temp usually 21 - 22°c + 10 % at a outdoor temperature of minus 3 to -5 which can happen in the winter months so there should be extra available transferable heat built into a system as the seasons change .
What radiators do you have fitted ? traditional panel type usually 600mm high x a certain length either one or two panel in certain circumstances even 3 panel in renewable energy installations. Kop

 

[John.g]

I would think heating requirements might be based on a -5C ambient to 20C room temperature, so 26C should be achievable from a ambient of 1 or 2C.
The rated rad output is based on a "50 deg" rating (flotemp+return temp/2 minus the required room temp. Realistically, max flow/return temps of 75/69C with a required 26C room temp results in a "46 deg" rad with a output of (46/50)^1.3x100, 90%, practically speaking you may have flow/return temps of 70/60C resulting in a "39 deg" rad with a output of only 72%.