Firebird Boiler cycles 3min on 3 min off ?

[manxy]

Hi everyone Merry Christmas to all.
I have a Firebird popular 90 fitted 1998. Open vent gravity/ hot water cylinder, 9 rads with TVRs. Problem is when I have all rads on boiler fires 3 mins on 3 mins off continuosly, even if i turn all down to half. The best cycle I can achieve is by turning all rads off, and only running 3 downstairs on very low. Even then the best cycle I can achieve is 3 mins on 7 mins off. Costing a mint in oil to leave them on all day in the cold weather.

Boiler thermo is always on the lowest setting of 60c cuts in and out at a 10 degree cooling, no air in system, pump is fine, rads heat up fine. 3 rads do not keep us warm. Any Ideas would be a great help.

Thank you for any help or advice.

 

[WHPES]

Is your room thermostat functioning correctly? Where is it positioned (not above a radiator I hope?)

Do you have a thermostatic radiator valve in on the radaitor in the room which contains the thermostat? (shouldn't have)

Do the motorised valve and programmer fucntion correctly?

You are probably best to get an engineer in if it is a fault with the boiler?

 

[kimbo]

Have you got thermostat on cylinder and thermostat in house, sounds like it is short cycling on its own control stat.You psted when I was typng whpes.
If the hot water is on gravity you should have a thermostat to control it linked to a two port valve, this may be stuck in the open position.

 

[WHPES]

Ah never thought it wouldn't have any thermostatic controls with it being fitted as recently as 1998. If it doesnt then you need controls on the system or it will be burning oil like nobodys business! (Google "S Plan" for a detailed explanation)

 

[manxy]

Thank you WHPES and kimbo. The only thing I see on the HW cylinder is the immersion unit on the top of the tank. We never use it and it`s switched off all the time. Also no room thermo. I see no valve or other thermo anywhere on the cylinder or on the cylinder pipework. Only the boiler thermo set at it`s lowest 60c.

Boiler was serviced last month and is working fine.Told the engineer about it but never really got an answer, he was off to another job in a rush. This has been going on for a few years but only really took notice when I retired and was in the bungalow all day. Also the cost of oil going up. We cannot carry on like this. If it is that we do not have these valves/thermo`s on the tank, is it a big job to get it done ? and what cost approx ? Thank you so much both of you for bothering to reply,we must get this sorted out.

 

[kimbo]

Fairly easy job for a good engineer. I can't give you a price because I don't know how easy it would be in your property plus different areas different prices. Get some prices from two or three engineers . If you check the oftec website for an engineer in your area you should be ok. Good luck.

 

[Best]

Hi Manxy! First of all, I would think it could be the boiler stat, but I am wondering where is the boiler sited?
If the boiler is outside & the pipes are badly fitted below the ground, ( in the damp cold ground ) then boiler will cycle like this, no matter if boiler stat is low or high. Pipes can lose most of their heat in 1 or 2 metres if surrounded in dampness & not ducted. No exaggeration. Hopefully just your stat.

 

[WHPES]

First you need to have the boiler thermostat etc checked then in order to run your system efficiently what you need to ask is for the system to be converted to a thermostatically controlled S plan system.

 

[manxy]

Hello Best, thank you for reply. The boiler is in the garage, but all the pipework is above ground. if i turn the stat up the boiler will come on with around 8/9C diff which seems ok. As I was telling Kimbo the only control I have is to turn off rads and turn down the ones I am using.Even then the best cycle I can achieve is 3mins on 7 mins off, and is just eating oil ?

 

[Best]

Seems then that you need boiler control stat checked. Agree with other replies, that you need to improve your system with full controls.

 

[manxy]

Thank you Best. The thing I don`t get about the boiler stat is the chap who serviced the boiler turned it up and down and it was coming on and off ok with a difference of 7/8c which he said was working correctly ?

 

[WHPES]

The system cannot work properly if there is 1/2 of it missing. Its possible that the boiler thermostat may be faulty but you can't tell for sure until you have a complete system. Its a bit like not knowing if your PC works properly when you don't have Windows loaded.

 

[manxy]

Point taken. I doubt if I`ll get a plumber up to the house just now with xmas a few days away. But I`ll get on it after xmas and suggest your advice on an S Plan thermo system. I`ll let you know what comes of it