honeywell st9420c

[cropstar]

Hi there

sorry if this has already been covered in previous threads but I couldn't find exactly what my query is when I did a search.

I recently moved into a new flat and it has a honeywell st9420c system installed with a wireless thermostat on the wall in the hallway. I can't seem to get the heating to come on when it is meant to. I have downloaded the instructions, but cannot for the life of me work out what the problem is. It comes on in the morning, but the wireless thermostat has a standby sign on and then in the evenings it has a flame sign which from what I understand means heating in demand, but none of the radiators come on. Even if I put it onto continuous, it still doesn't come on. The temperature is set correctly, but maybe I am missing something really obvious?

I can't phone the helpline because it's opening hours are during my work hours, so any help gratefully received!

Thanks!

 

[D_Hailsham]

1. Have you replaced the batteries in the thermostat and are they good quality, i.e Duracell? (Rechargeables are no good)

2. Is the clock correct, particularly AM/PM?

If both are OK, remove the thermostat from the wall and hold it near the programmer. Does the problem now go away?

Which instructions did you download - user's or installer's?

 

[cropstar]

Hi there

yes have replaced the batteries with duracell and the clock is correct.

I will try and pull it off the wall when I get home from work this evening.

These are the instructions I downloaded, just says user guide:

www.honeywelluk.com/documents/user-guide/pdf/1109.pdf


Thanks!

 

[D_Hailsham]

Here are the Installation Instructions.

You should find them more helpful.

 

[cropstar]

Thank you!

Still no luck. The thermostat seems to think its 26 degrees which it definitely isn't. Have tested signal strength which is fine and have tried setting the desired temperature really high to see if the heating will come on. both the programmer and thermostat have the flame sign but none of the radiators are coming on. Bit of a puzzler.

It has the optimisation sign as well but can't see how that would effect it?

 

[D_Hailsham]

Make and exact model of boiler?

 

[cropstar]

I can't find any paperwork about the boiler, but i think it is copperform indirect cylinder grade 3, does that sound about right?

The heating was on this morning but at a very low temperature.

Thank you so much for your help!

 

[D_Hailsham]

I can't find any paperwork about the boiler, but i think it is copperform indirect cylinder grade 3, does that sound about right?

That's the hot water cylinder!

The boiler is probably in the kitchen. Here is a pic of a typical gas boiler.

View media item 82571
Do you have any valves near the hot water cylinder? They will look similar to this.

View media item 5946 View media item 11762

 

[cropstar]

Sorry, complete brain fart. There is no boiler. I live in a block which is owned by the council and before I moved in they re did the entire heating system so there is one centralised gas system which is shared between us, a school and youth centre all next door to each other. I don't pay a separate gas bill, it comes as part of the service charge for everything in the block. Just to over complicate everything!

Yes there are 2 cylinders like that.

Thank you again!

 

[flameport]

It has the optimisation sign as well but can't see how that would effect it?

Optimum start or similar works by delaying the start time, so that when the 'on' period starts, the heating might not start then, but will operate some time later depending on other settings and the actual temperature etc.
If someone has set the thing incorrectly, it could have various unwanted effects.

Suggest you reset the programmer to factory default. Instructions will be in the manual.

 

[D_Hailsham]

Yes there are 2 cylinders like that.

Thanks for the info about the boiler. I assume you mean two valves like this:

View media item 11762
One will be connected in the pipe to the hot water cylinder, the other goes to the radiators.

I note that you are in a council property, so you should call them first as they have a legal responsibility to maintain the system. However you say you can't phone them. Don't they have an emergency number and have you checked their website? They may have an email address for maintenance requests.

It sounds as if the heating valve may be faulty.

1. Set HW and heating OFF
2. Move the metal lever on the ende of the valve from Auto to MAN.
You should feel some resistance and the lever should move back to AUTO when released.

3. Remove stat from wall and go to the HW cylinder (check signal is OK)
4. Turn the stat down to minimum
5. Turn heating to continuous
6. Turn stat to maximum
You should hear the heating valve working and the lever should feel loose in the slot

If it passes these tests but the boiler still does not work, we are now down to electrical tests. How confident are you about doing these? If you are, do you have a multimeter (and know how to use it )?

 

[cropstar]

Thank you for all your help!

Tried everything and no luck. I don't have a multimeter and probably wouldn't be able to use it if I could get hold of one! The council own the freehold, but I own the flat so I don't think they will send anyone into fix it, but it's worth a try!

 

[D_Hailsham]

Tried everything and no luck.

At which step in my instructions did it fail?

The council own the freehold, but I own the flat so I don't think they will send anyone into fix it, but it's worth a try!

Sorry, I assumed you were a council tenant.

There must be something in the documents about the purchase of the house saying who is responsible for what. It could be in the lease (assuming it's a leasehold flat) or the service/maintenance agreement.

 

[JohnD]

If you have a central heating system with one big boiler, how do you pay for your heat?

Do the owners of the heating system turn it on in summer?

 

[D_Hailsham]

Do the owners of the heating system turn it on in summer?

Good point.

Have you checked with your neighbours that their heating is working?