Hot Water ignite/switch off pattern - is this normal?

[t45]

Hello,
Is it normal that when I switch the hot water on to heat up, it fires up the boiler (the flame ignites) and then switches off (flames off) after a couple of minutes.
This process repeats ever 2-3 minutes, firing up and then switching off; this is a time sequence that i noted:
fires up/on 4:53 off 4:57
on 5:02 off 5:04
on 5:09 off 5:11
on 5:16 off 5:18
on 5:23 off 5:25
on 5:31 off 5:33

My question is: should the flame stay on once it is fired up of is this on/off pattern normal?

I have just moved into this property so do not know if this is normal or not - i do get hot water but it's this recurrent pattern of firing up/firing off that seems odd. Or is this actually normal? Should the watre heatre switch on and stay on for the allotted time to heat up water and then flame off as opposed to the above 2-3 minute interval?
Any ideas would be most appreciated,
Thank you

 

[picasso]

Its not normal for your boiler to cycle like this, a bit more information is needed like boiler make and model, what controls you have and pictures if you know how are always helpful.

 

[t45]

Thank you - it is a Kingfisher 2 boiler - we think it could be about at least 15 years old - it's quite old fashioned - the cylinder tank is for the hot water and is old fashioned - we have just moved in so dont know the history of it but in the loft there are two tanks - one the header tank and another.....would you know if this job is repairable or would a new more uptodate boiler system (like a combi) be required?
Also what would be the avergage cost of either a repair or new boiler - thank you

 

[picasso]

Check the boiler stat is turned up to at least 4 or 5 , the stat controls the temp of the water leaving the boiler between 55c and 82c so if set too low it will cycle.

 

[dcawkwell]

Thank you - it is a Kingfisher 2 boiler - we think it could be about at least 15 years old - it's quite old fashioned - the cylinder tank is for the hot water and is old fashioned - we have just moved in so dont know the history of it but in the loft there are two tanks - one the header tank and another.....would you know if this job is repairable or would a new more uptodate boiler system (like a combi) be required?
Also what would be the avergage cost of either a repair or new boiler - thank you

The boiler has no modulation it is just on or off.
The hot water tank can't take the heat that quickly so the boiler has to cycle.

 

[t45]

Thank you Cawkwell and Picasso

we had BG out who said we need a completely new system - i'm a bit unsure as it could just be a problem that could be repaired or is it just BG just wanting to sell a completely new system and install it at what price they suggest? they've already booked us in for a quote and for their engineer to call around and passed on a £400 off coupon in advance.

From what i have described in terms of the interval pattern, does this sound like this could be repaired as opposed to a completely new system installed?

Is this a job that is actually repairable, maybe a new valve or part required?

If a new system is indeed required, what is the best way/most cost efficient way of going about finding a local surrey based engineer/plumber to install and advise of the appropriate boiler.

Also if a new boiler is required, is it best to shop around and buy one myself and then find someone to install it or go with a company who supplies the boiler and installs?

Happy New Year!

 

[t45]

Should have mentioned the make of the boiler: it is a KINGFISHER (Potterton) - conventional style - think 15-20 years old

Is it better to have a combi boiler?

 

[dcawkwell]

Should have mentioned the make of the boiler: it is a KINGFISHER (Potterton) - conventional style - think 15-20 years old

Is it better to have a combi boiler?

Its working so wouldn't go to the extent of a new system.
Sounds like you have an old hot water tank with a big coil.
Or gravity hot water.
You could go to the expense of a new cylinder. Or just leave as is
until something breaks then look into it.
Check what it does on central heating. If it does the same on central heating possible just thermostat that needs replacing.
The Kingfisher will probably outlast you something that can't be said of a modern boiler.

 

[t45]

Thank you Picasso,
I tried with the stat on first 3 and then 4 but it still cycles as follows:

stat on 3:
fires up: 12:58 off: 1:02
fires up: 1:06 off: 1:08
fires up: 1:12 off: 1:14
fires up: 1:20 off: 1:22
fires up: 1:27 off: 1:29


Stat on 4:
fires up: 1:34 off: 1:36
fires up: 1:41 off 1:43

|This is when the hot water is switched on without heating.
I am going to try this with the heating on and see what happens.
Will report back.
Thank you for your help.

 

[t45]

Thank you Cawkwell,
I will try with the central heating on to see if it continues to cycle.
It is an old boiler - kingfisher but as you say it has not broken - we still get hot water - only it cycles - how long would a boiler keep going on this type of cycles?
And we have no problem with the central heating - this works fine although the radiators are old too and need to have thermostats fitted.
I am going to try with the heating on and the water....will report back......
When the BG engineer came out last week, we paid £90 but he did not offer a diagnosis but only said that we needed a complete new system, booked us in for another BG engineer to come around to give a quote for a new system and then gave us a £400 off voucher for use when buying a new system!!
For the £90 we should have at least got a diagnosis!!!!!We have requested a free of charge recall as it seems we paid the £90 to be told we needed a new system yet the heating works and the water does work but it just cycles and nothing has broken!!!!

 

[ianmcd]

it sounds like you have a gravity hot water system, you do not need a new system but it might be economically viable to have your existing system altered to fully pumped, I personally wouldnt ask BG to do the alteration but that is up to you, when you turn the heating on at the programmer can you get CH on its own or does the HW automatically come on at the same time ?

 

[t45]

Thank you Ian.

I have ran a few tests on the hot water/central heating system, first central heating only, second central heating and hot water, third central heating only with the following results:

When I selected heating only there was no cycle of the flame fire on/fire off and the central heating worked as normal.

However, when I switched Heating and Hot Water on together the flame fired on/fired off in the following sequence:

6:53 Flame fired on 6:58 Flame fired off
7:00 on 7:04 off
7:07 on 7:11 off
7:13 on 7:41 off
7:19 on 7:23 off

When I then switched the hot water off and kept the central heating on I got the following fire on/fire off cycle:

7:38 on 7:41 off
7:43 on 7:47 off
7:50 on 7:55 off

The fire on/fire off cycle seems to happen when I have only hot water and also when I activate the hot water when central heating is on, and also when I switch the hot water option off and leave the central heating on. If I select central heating (without hot water) the system works as normal with no cycle.

Any ideas what the problem is and what possible repairs will be required?

 

[ianmcd]

OK in a very complicated way you have answered a very simple question , the fact that you can select CH on its own without the HW coming on automatically means that you have a fully pumped system , so do you have one three port valve (y plan) or 2 x 2 port valves (S plan )

 

[Blagard]

OK in a very complicated way you have answered a very simple question , the fact that you can select CH on its own without the HW coming on automatically means that you have a fully pumped system , so do you have one three port valve (y plan) or 2 x 2 port valves (S plan )

I would be careful about such an assumption. I have seen where people replace an old programmer with a new one that allows selection of CH only when in fact they still get hot water with it due to the old open gravity circuit.

It would be interesting if the OP can tell if the pump is running when HW only is selected or if they are able to identify what (if any) motorised valves are fitted.

 

[t45]

Thank you Ian,
I’m not too sure what type of valve but I am guessing it is a 3 way and i only have one....do you think the valve could needs to be replaced and would this possible help?.....