Alpha 240E - Questions & Issues

[Part-Time]

Hello - not sure if this appropriate - multiple questions/issues in one post however this is my 1st post so here goes - and apologies for anything which is not clear or sounds stupid;

Make/model - Alpha 240E combi

1) Over the weekend I drained the CH, added cleaner, re-pressurised and left the systems fully on for many hours. Next day, drained and flushed with mains, via the filling loop and added inhibitor. Also took the opportunity to replace a leaking radiator value. The problem was this - after re-pressuring the system, ensuring all radiators where bleed correctly - except a towel rail in the bathroom which has no bleed point (!?) - and the pump in the boiler was bleed, the boiler refused to initially ignite. This happened both times following drainage.

The symptoms where;

a) Fan starts
b) Gas not released to burner, hence rest of ignition system halted

I am assuming that the gas not switched on due to something - air somewhere else in the boiler and therefore no water being pumped around? On both occasions, after a 30 to 40 minute period, of switching CH on (and DHW) and off, leaving the system on (for a few minutes - during which time boiler makes a whining noise), and leaving the system off, eventually life restored and no further problems.

My concern is, as the expectation that sometime I shall need to drain the system again, is there anything is I should be aware of to do/perform.

2) Second issue - there is a slight leak from the CH return isolation value (22mm connections), which has 2 inputs (return and filling line) and 1 output (boiler) - is this a standard item that is readily obtainable as on this boiler the value comes with a water filter (removable) The leak is actually coming from the isolation value itself, but only when under pressure, i.e. when filling system via filling line, rest of time no leak but clearly in need of attention.

3) The temperature of the hot water is not high enough. Having read through various material, including a lot of the posts here, a probable cause, and therefore 1st place to look, is the CH/DHW switch not activating sufficiently, and therefore insufficient water is diverting from CH to the DHW heat exchange - how can this be tested?

4) There is some evidence that there has been some internal leaking in the past, but not currently - there are 3 places of leakage evidence;

a) The aav
b) The prv
c) DHW expansion device connection (no device connected)

If I experience any future problems with the above could someone please advise if these items are readily available and replaceable.

Many thanks for any replies.

Paul

 

[Gasguru]

1. The boiler may be full of air and hence the differential pressure switch is not activated...it's the microswitch on top of the diverter. Replace the automatic air vent (the brass lump screwed into the top of the pump) since they often leak or block. When you refill the boiler turn the gas off, run the heating and alternately turn the hot tap on/off several times until the pump runs quiet. ie eliminate all the air through the auto air vent and into the rads. It's also worth running in heating and turning the power off several times to force air out of the aav.

2. I would imagine the valve is still available.

3. With the heating completely cold run the hot tap fully open. Check the heating flow (left hand side) pipe does not get hot and the nearest radiators do not heat up. If so the diverter is sticking so refurb or replace. Alternatively the plate heat exchanger may be partially blocked - straightforward to clean out. It could be due to other faults but the forementioned are the usual culprits at the age these boilers are now.

4. The aav is about £5.00 to £10.00. The prv about the same; all standard Caleffi parts. The "DHW expansion device connection" is probably just a washer'd connection so easy to reseal.


One of the best combi's ever made but by now are requiring a little tlc.

 

[Part-Time]

Many thanks Gasguru for your reply.

I've read carefully your points, particularly the 1st point and believe I understand and next time I fully drain the system - which will be soon as I would like to deal will all these niggly issues, and perhaps not so niggly issues properly in the near future - I shall try these good ideas, as they make good sense to me and let you know how well thing go. Regarding the DHW temperature I shall check this and if there is indeed a problem then I'll look to clean/remove blockage within the heat exchanger.

It is quite reassuring to note that the parts are/should be still available and cheap. I have to agree with you, generally the boiler has caused no problems. We've only been in the house 18 months and no problems. I know the boiler was installed in '98 but I do not think the previous house owner had the boiler serviced ever - certainly no evidence of this. I find the boiler quite logical to understand and there does not appear to be any significant bad design points.

Once again many thanks for the excellent reply and I'll advise how things go.

Paul