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[GaryBC]

My initial problem was no heat from the vents whatsoever (although with the a/c pump running I get chilled air out plus, when making various selections on the control panel, all sorts of flaps and valves can be heard moving behind the dash, and the airflow changes accordingly) so, after trawling through all the threads I could find on the topic, I changed the HBV and flushed the heater matrix (some brownish fluid came out but it was not particularly cruddy).

What I have now is a definite improvement in that the air output is warmer - but it is still far from hot. Plus, the heat output is erratic - with no apparent pattern between when it will deliver warm air and when it won't!

Two questions spring to mind.

1) Even though flushing the heater matrix appeared to show full and clear flow, could it still be furred up a bit? Is there any likely gain to be had in running some sort of commercial domestic de-scaler through it?

2) This is about a component I don't think I've ever come across a reference to here. It sits under the coolant header tank and appears to be some sort of inline pump (it is in the heater water circtuit - between the HBV and the matrix). If it is a pump, and it is not pumping (or not pumping consistently), could it cause the symptoms I describe?

[Entwood]

Couple of thoughts ... try disconnecting the vaccum pipe to the HBV... vaccum switches OFF heat .. so with the vacuum disconnected you should get full hot water flow. If you do it points to a control failure ..ie .. its giving vac when it shouldn't.... , if you don't it points to a waterflow problem... at least we know which side to look at !!

The component you refer to MAY be the climate control winter recirculating pump .. don't know its proper name but on Elites it is there to continue to circulate hot water even when the engine is stopped, this allows the heating to be used, for a while anyway .. even with the engine off, until residual heat is used.

Page 131 mentions it ...

http://homepage.ntlworld.com/andrew.reynolds983/Manuals/Omega2002Manual.pdf

HTH

[GaryBC]

I pulled the vac pipe and nothing changed - so it must be the water circuit, yes?

So, what's next? Do I have a go at a chemical de-fur of the heater matrix? If so, has anyone ever done this before? Any pointers as to what to do/avoid?

[Entwood]

Before "defurring" ... descaling ?? .. I'd try a flush with a hose pipe and see if it flows freely, then refill and make sure you "burp" the system to get out any airlocks... . If it does and the problem continues I would suggest the HBV is failing internally..   but you've just changed it ..

[GaryBC]

Yeah - descaling! Like what you do to a kettle or a steam iron.

I fitted a new HBV the other week and flushed the matrix out at the same time. Initially the water ran very slightly brown but very soon turned clear. I flushed it two or three times in both directions and the flow seemed ok with no apparent back pressure. I took all this as evidence that the matrix is ok - but it obviously ain't as I only get tepid air in the cabin (even with the HBV vac line disconnected).

What is this 'burping' you mention? I thought the whole system was self bleeding?

[Entwood]

To "burp" the system start engine with the header tank cap off, and the heater controls set at max heat. Leave to idle until the thermostat opens, as felt by hot water flowing through the pipes to the radiator.

Take hold of the largest pipe and give it a sharp, firm squeeze then release .. do this 5 or 6 times .. you'll see the level in the header tank rise as you squeeze then drop back as you release .. with any luck you will also see bubbles as you move any airlock.

Wait a couple of minutes and repeat.

At this point it might be worth feeling the pipes that lead from the HBV to the heater and seeing if they get hotter when you squeeze the large pipe.

HTH

[GaryBC]

I'll give it a go - cheers!

[GaryBC]

Well, I gave it a go and it's made no difference.

Is it now time to try some de-scaler, maybe?