Vaillant Turbomax 828E needs attention

[Milsec]

I need to find someone in to look at this 3 year old boiler. IMO it ha

a sticky and/or defective divertor valve (see below for a list o symptoms).

I was wondering if anyone could recommend any good, reliable and fairl priced heating engineers in the NW London area?

Thanks all.

_Fault_description_

1) Divertor valve sometimes makes a grinding noise as it move position. (Has done that about 6 months after installation, but everything worked fine.)

2) No hot water on demand when heating is on sometimes,and radiator become very hot and boiler indicates (green light flashes) that tha it is heating hot water for the hot tap even after hot tap has bee closed and no hot tap is open.

This tends to happen usually when the central heating has been on (ie the boiler is fired up already and hot). The condition persists even if the boiler is switched off at mains an then on again after say 10 -20 seconds. Turning the hot wate temperature control knob to off and then on again can stop the gree light flashing, but does not restore normal hot water delivery.

It seems divertor valve has seized when this happens.

Boiler has to be switched off at mains and left to cool down for som time (at least an hour or more) to restore normal operation.

There are times when the valve only partially opens because luke war water comes out of the hot tap.

Recently the divertor valve has been know to stick from cold (firs thing in the morning when heating is off.

3) Boiler goes into warm start mode during the night (when heating i off). Radiators get warm and boiler cycles on and off frequently (e.g 2 mins on, 30-40 secs off). Boiler shows yellow light and flashin green -- no hot tap was opened when this occurs.

4) General performance of boiler is erratic. There are constant pump overruns when the boiler switches off eve though demanded temperature from the room stat has not been reached And this happens when the boiler isn't in the fault mode described i

2) or 3)

-- Milsec

[Lee]

Don't know of any, changed the valve on our 828e myself, it's very easy to do on this boiler :)

Lee

[Milsec]

Thanks Lee,

I may have had a go if the weather was milder, and may do if I stil haven't found some one by then. Give us a few pointers then, especiall about draining the system and making sure that you don't get water o the electronics box! By the way did you have all of the symptoms I have especially th excessive pump overuns and funny warm-start behavior?

Milse

-- Milsec

[Lee]

Turn off the power first ;) All I did was close off the boiler shutoff valves and drained the water from the boiler, carefully :) (It's obviously not necessary to drain the whole system if using the shutoff valves) Others here have suggested not using the built in drain points on the valves, as they may leak apparently, but they worked fine for me. It is possible not to spill any on the PCB if you are careful, but obviously protect it with something absorbent if you want.

The valve itself is easy, but don't forget to change the O rings, washer and clip - it should come with new ones. Mine did.

Yep :) Especially the warm start malarky, which I turned off because it was aggravating the problem. Like yours, the valve on ours was noisy from the start, but the new valve is almost silent.

Got the valve here:

them cheaper, but this place delivered next day :)

Lee

[Ed Sirett]

I think your diagnosis is quite correct. You can switch off the warm start feature by turning the DHW control to minimum and then back to the previous setting. The green light will then only flash when a tap is running.

The diverter valve is £100 (available form A10 boiler spares and doubtless online).

If you try to fix (rather than replace) the diverter it will fall apart so don't try until you are ready.

Email me privately if you are prepared to wait a couple of weeks before I can help. With care the job can be done without a full drain down.

[Ed Sirett]

I agree this is a straight forward job and the price online is a lot better than the spares shop. I've never had any trouble with the boiler isolators or drain off valves on this model.

[Milsec]

Ed, Lee thanks for the feedback.

Yes I've had a look at the valve (I hope it not soft brass, otherwis I'm definitely not touching it). But there has been some recen developments:

1) Warm start can't be tuned off anymore. Turning the water temperatur knob to the left and back again still leaves the green light on. 2) Got an F.22 error. Very strange indeed since there was and is wate in the system. I turned the boiler off, waited 10 secs and then powere on again and it worked as usual. Maybe it was crud in the syste stalling the pump?

I'm hoping these are related to the valve sticking and out of syn states(?) and nothing more.

By the way, what is anti-cycling, and what does Part load settin (d.00) mean?

Regards

-- Milsec

[Ed Sirett]

When you have fixed the diverter valve I suspect the other problems may disappear. Note there is something of a detent at the end of the DHW knob's range. Try giving turning it a little more a the lowest end.

Anti cycling is a delay imposed by the controller to reduce short cycling. AFAIK the delay is the same whether it's from the internal or external thermostat being satisfied, but it is temperature related (hotter makes it shorter).

The parameter d.02 is a modifiable one which can be used to adjust the anti-cycling delay.

The parameter d.00 is also adjustable and can be used to adjust the maximum power of the burner in heating mode. It goes from 0 to 15 I expect the 0 maps to the lowest setting i.e about 40% of full power.

HTH