Changed DV on Ravenheat 820/20 problem with DHW

[ChrisR]

I think you mean the green bit is plastic - which I confirm by looking at the one I got from BES. That's actually the CH outlet, it doesn't go to the pump.
There are only 3 variations of these diverters really, other than changes to microswitches or rotatable parts. Those three have the inlet/outlet ports in different directions on the brass diverter casting. I don't think you'd be any better off with the part you're thinking of (from BES). Whether the original Giannoni DV's, assuming this isn't one, are any different in their resistance I don't know, but I doubt it.

The resistance is determined by the gap left when the moving parts move (red)
I haven't bought a giannoni of this type recently, but not that a similar DV for an Alpha boiler (£100+) also has the green part in plastic.

Give BES a ring and see what they know...!

SEE HERE

 

[MikeG]

I did contact BES to find out what the difference was between the 3 DV valves they supply which look similar but have different part numbers.

They reply back indicating they are all the same it their operation, the difference was the fitting positions of the side inlets.

I must also say that they have suggested that I return my DV valve which has a broken plastic assy for a replacement.

In the meantime I have ordered the original valve and it arrived and from what I can see in terms of the valve action and how much each of the valve opens I think they are both identical.

Hence I am a little concerned why I have experience a change of behaviour of the DHW after I changed the valve this time round whereby when I open the hot water tap the boiler lights up and the flame appears to be red at the top and secondly the hot water is going into the central heating circuit and as a result what comes out of the hot water tap is not hot enough. Although the heat exchanges has two separate circuits for DHW and CH.

I haven't changed anything or settings etc, the only thing I did this time round as I changed the DV for the second time is I used the new micro switches which were supplied with the BES valve instead of using the original thereby I had to disconnect the wires from the two switches, could it be I have might have mixed the wire connections and maybe the electronic controller is sending different signals.

On my boiler I have 2 of these micro switches with I think 3 wires each.

Any ideas?

 

[pannierstan]

You have a passing D/valve. Not unusual from BES from what I have heard and experienced.

Stan

 

[MikeG]

You have a passing D/valve. Not unusual from BES from what I have heard and experienced.

Stan

Thanks Stan! for putting my mind to rest. I will be replacing the newly fitted BES D/V with the proper one on Saturday.

I will report back my findings.

MG

 

[MikeG]

Just to let everyone know, I finally managed to open up the boiler again...(lost count how many times I have opened it now! and bruised my hands and fingers..

I replaced the BES supplied DV with a proper original valve cost £180. I compared once again the replacement D/V with the original type. To tell you the truth there is no difference even the push action of the center pin also identical.

Nevertheless as many of you have mentioned from having used or known someone who has used the replacement valve I must also strongly advice not to go anywhere the replacement cheap valves otherwise you risk killing your heat exchanger.

After replacing the valve, pressured up the system and fired up the boiler by opening the DHW tap and out came nice hot water! and the radiators remained cold. The boiler ran extreamly quite no red flames or kettling which was apparent along with water hammer.

The heating also works very nicely too.

Never again use cheap replacement parts!

PS.

One thing I noticed now is because I had opened the pressure release valve to reduce the pressure while filling the system with water because the pressure has risen too high it appears to be dripping slightly. It has never done this before. Will this settle down or I will need to change this valve also?

MP

 

[ChrisR]

The broken plastic part would have let the diverter "let by". Are you saying it was misbehaving before the part broke?

The prv is doing what they all do when old, leak if opened. You can try opening it again and letting it snap shut, or you can take out/clean the valve seating part, but it's probably worth getting a new one as the old brass parts may be rough too.

 

[MikeG]

The broken plastic part would have let the diverter "let by". Are you saying it was misbehaving before the part broke?

The prv is doing what they all do when old, leak if opened. You can try opening it again and letting it snap shut, or you can take out/clean the valve seating part, but it's probably worth getting a new one as the old brass parts may be rough too.

I think the plastic part broke almost immediately maybe it was not aligned properly and the very first time the water pressure was applied it snapped.

In the original part this fitting is made of brass! therefore no chance of snapping and getting logded in the system...clearly the replacement part is of poor design especially when you have hot water going thru it.

I did check whether the plastic part made any difference but I think it ensures the moving pin is kept central during operation and it could have been the factor behind my problem. I have kept the valve maybe if my new original valve decides to leak i might take the brass fitting from the original and install.

I think it was a waste of time having got the BES DV.