ALPHA BOILER GUSHING & TRICKLING NOISES & NO CHW

[wendiff]

Hi everyone.

I was here around a year ago and you all really helped solve my then problem - my 10 year old Alpha 240P got new DV and manifold and 6 months later a new HE. Before & after the HE prob (should have changed it with the rest!) the boiler was working really silent and smooth again... that is until its got really cold! Please someone point me again in the right direction for following problem.

DHW works ok (possibly too hot) but as soon as I switch on CH I hear a gushing, trickling and other water sounds and boiler doesn't fire up (or if it does it fires down after just a few mins).

I presume I have air block (don't know how?) and from reading other topics have seen I should try to release pressure via valves near pump (and on EC?) but I may be barking up a wrong pipe!!! (Could it be lack of new inhibitor, cleaner etc, or any others such as sensor failure?)

Hope someone comes back soon as am very cold and am still unable to afford to change boiler.

Wendi

 

[Gasguru]

Appears to be no flow to the rad circuit..perhaps the return filter is completely blocked. Did the problem suddenly arrise or has it been a gradual problem.

 

[wendiff]

Hi gasguru, many thanks for quick reply.

Water seemed rather hot past week or so but I only noticed noises today so I think its been fairly sudden.

Some good news... after posting I released the 2 valves (EC and Air Vent) as suggested in other topics and even spun the pump. It has definately helped as boiler now fires up and rads are hot but I still hear some trickling/crackling noises so not sure how long it will last or, if fixed, what can I do to help prevent it blocking again?


Wendi

 

[Gasguru]

I released the 2 valves (EC and Air Vent)

EC valve? Hope you don't mean the expansion vessel.

The auto air vent cap should be left loosened a couple of turns. There must have been a significant amount of air trapped in the pump to stop the heating.

 

[wendiff]

Oh dear!!!

I did mean the expansion chamber! ... the "big red thing" (as described by another regular) on the back!

What have I done? Air hissed out and it is still working with very little noise but have I damaged anything?

worried
Wendi

 

[Gasguru]

The expansion vessel is presurised with air. The air pressure exerts a static pressure in the system to enable the water to reach all the high points. The vessel also serves a second purpose...as the water in the system is heated from say 10 to 85 Centigrade it will expand in volume by a few percent. The vessel takes up this expansion volume.

The cold pressure in the system should be about 1 Bar on the boilers gauge. When the system is fully hot ideally the pressure should not be more than 2 Bar. If there is no air in the vessel the pressure can rapidly rise towards 3 Bar opening the safety valve. Sometimes however there is sufficient air trapped in the tops of radiators (to act as an "expansion vessel") so limiting the pressure.

Next opportunity drop the system pressure down to zero and pump up the vessel to 0.8 Bar. Only check the vessel pressure with 0 Bar showing on the boiler gauge. If you leave it the vessel diaphragm can be damaged (a hole can be worn through it). See FAQs.


Out of interest which regular said release air from the expansion vessel?

 

[wendiff]

OK.

Thanks to your clear explanations have at least understood main gist, however have a problem as:

1) I am not sure how to "drop the system pressure down to zero" other than bleeding, bleeding and bleeding one of the 2 rads I have.

2) Not sure if I understood but does the Vessel have its own pressure guage? (Only check the vessel pressure with 0 Bar showing on the boiler gauge) as I can't find one!!!

It's late so I don't expect reply today but it you could explain how to do above would be exreeeeeeemly grateful.

Will get back to you with name of "regular" which I have on disc somewhere - perhaps I misread and he wasn't as "regular" as the 4 or 5 of you.

Wendi

 

[Gasguru]

Wait till the system is COLD and turn off the boiler then:

Bleed all the radiators.

Temporary close the auto air vent cap.

Drop the system pressure down to zero (shown on the gauge on the right hand side of the user panel) using the drain-off valve inside on the right (NOT the red capped safety valve). Note using the drain-off you will sometimes find they will not reseal ie will need replacing but this will be the easiest way for a diyer.

Using a tyre pressure gauge check the expansion vessel pressure...it will probably be zero since you bled out the air. Attach a pump (a cheap tradiational cycle pump is ideal) to the vessel and start pumping. Make sure the drain-off valve is still open. Give it an initial 50 pumps and check the pressure. You need about 0.7 Bar. Carry on pumping it up if neceassary. Expect water to flow from the drain-off while pumping up the vessel.

Now close the drain-off, open the auto air vent and re-pressurise the boiler to 1 Bar.


The pressure gauge should be checked weekly...it is critical to the longevity of the system.

 

[wendiff]

Hi gasguru.

Sorry to come back again but after managing to borrow pressure gauge and bike pump on reading your 2 last posts again I got a couple more doubts!

1. If I'm unlucky and the drain off valve does not reseal, as you say can happen, will that mean I cannot use boiler until it is replaced?

2. You said to check "next opportunity" so if your answer to my point 1 is that the boiler cannot be used till valve replaced can I wait till cold weather passed as it is now apparently running well and silently again, system pressure just a tad over 2 bar?

3. In respect of pressure "ideally being not more than 2 bar" my boiler has run between 2 and 3 for last 4-5 years despite bleeding and bleeding radiators which only drops bar temporarily (and despite HE's servicing it!). Is this bar acceptable or how can I bring it down to 2 or below permanently?

Thanks again a lot and a lot
Wendi

 

[MrPC]

3. In respect of pressure "ideally being not more than 2 bar" my boiler has run between 2 and 3 for last 4-5 years despite bleeding and bleeding radiators which only drops bar temporarily (and despite HE's servicing it!). Is this bar acceptable or how can I bring it down to 2 or below permanently?

Same here ( alpha 240eco ) and a string of engineers failed to fix that- and other problems.

 

[Gasguru]

1. If I'm unlucky and the drain off valve does not reseal, as you say can happen, will that mean I cannot use boiler until it is replaced?

It may drip a little - just put a bowl underneath until you can get a replacement part - very cheap.

In respect of pressure "ideally being not more than 2 bar" my boiler has run between 2 and 3 for last 4-5 years despite bleeding and bleeding radiators which only drops bar temporarily (and despite HE's servicing it!). Is this bar acceptable or how can I bring it down to 2 or below permanently?

With the expansion vessel correctly inflated most average sized properties with a combi would not normally see the pressure rise more than 2 Bar with a cold pressure set to 1 Bar. The pressure on your boiler rises higher due to the vessel being only partially pressurised. If the pressure gets towards 3 Bar the safety valve will open causing more problems. Vessels gradually loose pressure...often after 3 years they are flat. It is a good idea to give the vessel 20 pumps each year with a standard cycle pump. That will keep it topped up with air. Obviously this is not as accurate as depressurising the system and checking the vessel pressure but it's normally effective.

 

[wendiff]

Thanks again gasguru for your patient help.

All received well and clear. Hope not to bother again at least until I need to change my boiler when due to present laws I will have serious problems finding where to site it or finding one with an over 15m twin flue - several companies have been and none are convinced I can put it anywhere and why I am having to hang on to what I've got, good or bad, till the last!

Regards Wendi