Ariston Diverter valve leaking

[dresbo]

Hi,

Please help! I've got no hot water or heating and the missus isn't very pleased.

I have an Ariston 27MFFI which has leaked overnight from the top of the diverter valve where it meets the Actuator motor.

I read that I might have to replace the whole flow group (998613), but I thought I should just be able to change the seal. The service manual lists two parts at the top of the flow group:actuator bush (998974) and spring kit (998975), but will this fix the leak? I can get both from stock locally, but I don't want to waste my time or money.

Someone here previously suggested you could relace the 'gland' in reply to a similar question, but I wasn't sure what that meant or whether it was in the part sets I listed. He also said that it might have damaged the actuator motor?

 

[mickypeee]

i usually change the Atucator bush , and the 2 springs inside when they start to leak. Thing is you need to make sure you get the seriel number off your boiler when asking for the part number as i once ended up with the wrong parts as they changed them slightly.

 

[dresbo]

I managed to get the actuator bush and springs off this evening and can see that this does seal the valve.

I'll take the serial number and removed parts with me tomorrow just to be sure, and I'll report back on the results. Fingers crossed.

Thanks

David

 

[mickypeee]

i think there are 2 different parts for the same boiler. so best to make sure. Last time i had to wait a couple of weeks as they came from italy so i would be suprised if they have them on the shelf. Might get lucky tho.

 

[dresbo]

I managed to get the correct parts. They were a good match for the old ones and the boiler is now working. When I opened the panel I noticed the auto air vent was also leaking water, so I had to replace that as well (which was a complete pita because of the access).

All seems to be working, but the hot water coming out of the taps is colder than it was before. It's warm, but definitely colder than before, and makes the mixer in the shower almost too cold whereas it was fine before on the same setting.

Any ideas what could be causing it?

Thanks again!

David

 

[dresbo]

I did a bit more digging and the actuator is fine. I can see that the normal position is with the valve diverting to the hot water, but it looks like the valve isn't completely closing in this position and it's leaking into the heating. The heating pipe gets hot as I run the water which confirms this.

I'm nervous to take the diverter off as it has a lot of fittings. Anyone tell me how difficult it is to do, it seems to have a lot of connections. Do I need a new one, or can I just clean it. I notice there's a large manifold on the front. I wondered whether removing this would give access without removing the diverter from the bolier.

 

[petit_pablo]

What did you replace in the diverter?

Has it all been aligned correctly in the valve so that the push rod moves fully?

 

[dresbo]

I replaced the actuator spring kit and bush. It seemed like it would only screw in and align one way. Is it possible I screwed in the bush and spring mis-aligned? If so I'll drain it and take it apart again.

Since the default actuator position is DHW I took the actuator off leaving the pin exposed and ran the hot tap. I still got a hot heating pipe. There's actually another part on the service manual:Heating Spring Kit (998718) which seems the be the heating isolation part. Perhaps this might benefit from being replaced.

 

[dresbo]

Bingo!

You were right. I didn't realise the top of the valve in the diverter body needed to be aligned with the pin and it rotates in the seat. Once I'd centered it with the actuator pin and refilled the system it all works correctly.

Thanks for everyone's help with this.