Baxi boiler faults

thechief1979

Hi all,

Recently moved into a new home which has a Baxi Combi 105 HE bolier (age unknown, approx 8 years) that appears to be very unhappy! (faults listed below). Despite faults we still have hot water and heating to some degree.

- Upon moving in, pressure was low so refilled up to 1.5 bar. Over the course of a few of days, pressure dropped to zero again - assuming this was becasue boiler was leaking quite heavily! Have not refilled since as heard this is not good practice?
- When boiler is on, it omits a 'whistling noise' similar to a kettle boiling.
- Cold spots on all radiators (7 in total, all thermostat control) despite bleeding.

Any diy tips or guidance when dealing with the proffessionals appreciated.

Thanks,

latecomer

Sounds like a leak in the system. I would fill it back up and continue to top it up as required. The water in the system will have an additive which will be diluted over time as you add water but then at least it keeps the system running an should cause much if any harm.

If the radiators are old then they could have sludge build up in them but this would normally cause them to be cold along the bottom. Air causes them t be cold at the top. Where are the cold spots?

tiggerbodhi

Got the same Boiler.... and we have had eight visits recently from engineers so have a good deal of experience with this !!!!!!!

The loss of pressure and whistling will be more than likely a faulty pressure relief valve, often caused by carpy water quality in the system, you will need to get this replaced, fairly easy job and outside the combustion area so can be a DIY job, but you may prefer to get an engineer to do it.

once this is done and the pressure is out of the system take the long plate off the top and you will see the shrader valve for the pressure vessel, use a pressure guage to check this is at 12-15psi, if not use a bicycle pump to get it to this.

refill the system until pressured and bleed all the rads, but does sound like the rads are sludged up, personally from experience would remove each one in turn and flush them out with a hose in the garden, trying to flush the system in one, even power flushing may not clear it and often will push stuff through the plate heat exchanger that does the hot water killing it in the process, once the rads are flushed and the system works again add a cleaner (sentinel or fernox) run for a week and flush again, then refil with an inhibitor.

You may want to get a "magna clean" filter fitted, really needed to protect a combi boiler.

If you hot water is not coming through very hot it is probably the heat exchanger blocked, not cheap to have done but worth it, if the HE is ok and still the water temp is low check the flow, it should be about 7-8 litres per minute, any faster and the water doesnt get a chance to fully heat up.

thechief1979

Thanks for the replys.

Got a local reputable heating engineer out to have a look (before i'd seen the replies to this mesage... doh!) who couldnt see a problem (didnt mind charging me £70 though! , he suggested getting a new boiler installed (he would say that though, wouldnt he?) as baxis are apparently unrealable past 5-6 years.

he did bleed radiators though which are a lot better, exceptone which is mostly cold apart from a thin 'strip' at the top. will try the diy approach to removing the possible sludge from this rad.

Kiran

Possibly take out a boiler service contract as these normally include a service before the cover starts. Also they wont charge you £70 for the pleasure of coming out.