Ideal Mexico Super CF55 fires for short time only

[maninalift]

I have just moved in to a new house which has an Ideal Mexico Super CF55 fitted.

The previous owner moved out the day before and tells me the boiler was working.

Next to the boiler, there is

* Switchmaster S400 switch
* drayton Mid Position Actuator
* Grundfos Selectric ups 15-50 pump

With the switch set to "constant" and "hot water", the pump runs constantly (EDIT: or at least it makes a noise) but the boiler only fires up for about 5 mins before stopping burning (pilot light stays lit). EDIT: the pipes entering the tank from the boiler do warm up, but apparently not enough to heat the water noticeably. I get water out of the taps but not hot water.

I haven't yet checked whether the boiler remains running if the CH is switched on. EDIT: now I have, with the CH on I have the same problem. Boiler burns of 5 mins, radiators do not heat up.

My apologies if I have missed any obvious important info out, I am totally green when it comes to looking after a boiler and very grateful of any help.

 

[Agile]

That is probably correct because the boiler does not modulate and is grossly oversized when only running the hot water cylinder.

Tony

 

[Boilerman2]

Sounds normal for an installation of this type & age Is your Hot Water heating up (it might take over an hour depending on the system design) if you are getting hot water then no fault if not check the feed and expansion tank has not run dry due to a stuck ball valve

 

[maninalift]

Sounds normal for an installation of this type & age Is your Hot Water heating up (it might take over an hour depending on the system design) if you are getting hot water then no fault if not check the feed and expansion tank has not run dry due to a stuck ball valve

No the water is not getting hot, I have tried leaving it all on for 24 hours.

I haven't got into the attic yet to check the header tank due to being out in the day / not wanting to disturb sleeping children in the evening / not having a ladder.

Arrrg! I will get up there as soon as I can.

If the seller is to be believed it was working just a few days ago which makes me think the system can't be dry and I must have missed something obvious.


... oh and thanks guys for the replies

 

[Agile]

Who would believe a house seller?

Killer contracts are apparently less than £5k so think what can be done with a £300k house.

 

[ChrisR]

Pump - not actually turning, or blocked,
Air in pipes/pump,
Sludge build-up.

Try bleeding the highest radiator.
If air goes IN, you're short of water.

 

[CombustionGuy]

What is the stat on the front of the boiler set to.
What is the pump speed set to.

 

[maninalift]

What is the stat on the front of the boiler set to.
What is the pump speed set to.

Right now, the themostat on the front of the boiler is set to "4", which the table printed on the boiler tells me means 71C or 160F. I have tried turning this right up to max (6 / 82C / 180F) to see if it makes a difference but it seems not to.

The thermostat on the tank is set to 65C. Again I have tried turning it all the way up.

The pump was set a max, I have tried turning it down (in desperation).

 

[shray]

Sounds normal for an installation of this type & age Is your Hot Water heating up (it might take over an hour depending on the system design) if you are getting hot water then no fault if not check the feed and expansion tank has not run dry due to a stuck ball valve

you wouldn't even get water out of the taps if the tank had run dry.

Either the pump is knacked or the zone valve is. on the cylinder there will be two pipes on one side, one about half way down and another directly below but near the bottom, check to see if they get hot when the boiler is on ? Also try the CH to see if that works, if it does then you can eliminate the pump being at fault but more likely to be the zone valve not switching.

 

[maninalift]

you wouldn't even get water out of the taps if the tank had run dry.

I don't get *hot* water out of the hot tap but I do get water.

Either the pump is knacked or the zone valve is. on the cylinder there will be two pipes on one side, one about half way down and another directly below but near the bottom, check to see if they get hot when the boiler is on ? Also try the CH to see if that works, if it does then you can eliminate the pump being at fault but more likely to be the zone valve not switching.

OK I will check the pipes and try the central heating.

 

[45yearsagasman]

you wouldn't even get water out of the taps if the tank had run dry

BM 2 is referring to the ch expansion tank.

 

[maninalift]

BM 2 is referring to the ch expansion tank.

OK, expansion tank not the same thing as header tank, got it thanks. Reading about it now to educate myself. I'm not quite sure how to find or check that but I will look into it.

 

[45yearsagasman]

From your description you may have two tanks in the loft.
1 Large cold water storage tank
2 Smaller CH expansion tank.(header tank)
You need to check the level in the smaller tank. Ensure that it has 4/5 inches of water in it.
Have you checked that your pump is actually working? Read the FAQ's for advice on how to do that.

 

[maninalift]

From your description you may have two tanks in the loft.
1 Large cold water storage tank
2 Smaller CH expansion tank.(header tank)
You need to check the level in the smaller tank. Ensure that it has 4/5 inches of water in it.

Thanks, I will check this evening.

Have you checked that ypur pump is actually working? Read the FAQ's for advice on how to do that.

No, I haven't. I assumed that because the boiler fires when the hot water system is first turned on, the pump must be pumping water down to it. The pump continues to make the same noise as the boiler cuts out so I thought it must still be pumping.

I will have a look at the FAQs for how to check the pump.

 

[maninalift]

Have just had an update from my wife who I asked to check the central heating.

Apparently that also does not work.

I will look into the suggestions so far when I get home tonight.

Thanks all for your help.