top header tank overheating

hi

we've got a pulsacoil 2000 boiler

Last night we were awoken by the sound of boiling water coming from the boiler. the top header tank had got water in it (approx 6-8 inches) although it was boiling in the top header plastic tank! had to turn it all off as it was setting our sensitive fire alarm system off due to the steam. the *boost* switch was turned on at the time too and its the first time it had been on since late feb. Have removed the front panel this morning to find the red led is flashing 2 times per second.

anyone got any ideas what this could be?

thanks in adavance

chris

Hi pick1982

Well this is one of those faults that is supposed to be impossible, but I encounter it once in a while. It's potentially VERY dangerous. It means the heater(s) are not turning OFF when the appliance is hot enough. Instead they are continuing to heat the water in the store until it boils, causing the header tank water to boil too eventually. Usually accompanied by loads of steam and condensation in the cupboard, and damage to decoration etc.

Early Pulsacoil 2000s have a thermostat in each heater, and a backup overheat protection thermostat to turn the heater(s) OFF if the main thermostat fails. Later versions have a dual function heater thermostat which is actually two thermostats inside one component. Either way, both the main thermostat AND the backup overheat thermostat must have failed in your appliance and it is dangerous to continue using it. You MUST get this repaired!

Unfortunately the usual cause of main thermostat failure is a water leak form the heater element, so yours probably needs new heater elements along with new dual-function thermostats.

Hope that helps.

Cheers, Mike

hi mike

thanks for the reply

ive turned the thermostats down slightly from the preset 73 degrees n its cutting in and out perfectly now.... any chance it could have stuck??? or is it stil best to get a qualified person to come check it out?

thanks

chris

Hi Chris,

The real problem is the overheat protection is not working and this is masked by turning down the main stat as you have done. I strongly advise fitting new (dual function) thermostats. Get them from www.segel.co.uk

Cheers, Mike

Mike the Boilerman wrote:Instead they are continuing to heat the water in the store until it boils, causing the header tank water to boil too eventually. Usually accompanied by loads of steam and condensation in the cupboard, and damage to decoration etc.

Hello Mike,

You describe the problem we are experienceing exactly.

This happened to us perhaps a year ago, when we woke to find huge amounts of condensation had damaged the airing cupboard. First time around I checked the header tank and noticed it was low, and, after topping it up, the unit resumed functioning normally.

Until yesterday.

Once again, everything in the cupboard has been damaged by dripping water from the roof, the header tank is extremey hot and the unit is making a heck of a racket.

Topping up the header tank has made no difference, and now that I understand this is a potentially dangerous fault, I have isolated the unit from the off-peak supply.

I have two questions:

First, please can you confirm that this is the the part I would need to obtain to fix the fault: South East Green Energies Ltd - Switch and Store Overheat Thermostat?

Second, can you confirm whether it is safe to continue to use the Boost (immersion) Heater in order to have some hot water until the problem is fixed?

We live in SW London, Mike - I will drop you a line and would be grateful if you coud reply to confirm whether you can assist with out boiler and how much this would be likely to cost.

Hi

The problem you are talking about seems to be exactly the same as ours as well!

We came home last night to find the top heater bubbling away and condensation in the cupboard. We do not have economy 7 electricity as no off peak supply was installed when the flats were built. The previous owners weren't sure how the system worked so advised us to keep one switch on all the time. I now think that we have had the boost switch on permanently for the year and this might be what is causing the problem. Do you think this could be the case? If so, if we sort out the timer would this solve the problem or do we have a separate problem with the thermostat that needs resolving?

Many thanks

The part you need is a MIP080, these are the retro kits for the thermostat. You can buy them on-line via this link: Gledhill Pulsacoil 2000 Spares

Hi

Would the top tank need to be boiling to require such a replacement?

My over head tank seems often quite warm. When it is warm it seems to coincide with more tripping out. It is noisy at these times. I keep it fairly well topped up tho.

There is evidence of some condensation and potential water splatter but I have not seen it boiling. However it has been before tripping? But why?

I do not understand this boiler. How is it warm, and is that normal? The "open vent" pipe, seemingly for air - or water? In or out? Why does it feed back into the top tank? And should it be under the water level in the top tank?

Any thoughts welcome. Mainly I would like to know should the top tank water ever be warm? Is that indicative of the problem above, even though it does still trip out? (and can be reset when it has cooled) I do not like the idea of it boiling clearly.