Issues on Sime Halstead Trio after water loss

[petkow]

I've had a Sime Halstead Trio Combi working without big problems for the past 12 years. I keep a tab on things like CH water pressure etc. Recently I had some people staying when I wasn't in, and they somehow knocked a radiator causing a leak.

Unfortunately not knowing, they kept running the system until it shut itself down. When I got back the CH loop was empy (0 pressure on the guage). I fixed the leak, topped up and tried to restart but got the most horrible groans. After a bit of trouble shooting I determined faulty recirculating pump which I changed like for like. Fired up again, and CH was all OK. Unfortunately though, HW is no longer functioning at all. When the boiler is firing for CH, I get a few seconds of hot water through the taps but it no longer auto-detects demand and is not swiching on.

Has anyone got any ideas? I am fairly technically competent being a quailified Mechanical Engineer, but heating engineers and plumbers around here have got so much more business to be bothered to listen, and all they want to do is replace the lot!

No sure about the insides other than stuff I can see but would replacing the diverter valve be worth a shot? Also, I have fiddled with the setting on the proportiong unit. I don't even know what this is. Can anyone enlighten me? I know I probably need a pro in, but I have been trying to find just that. A decent honest guy who has the time of day and will tell what the problem is.

Thanks so much in advance.

 

[gasmick2]

Hi ye sit sounds like a new diverter valve diaphram is required although it just as cheep to replce the whole unit not a difficult job if you look at the end of the diverter there is a micro swich turn on the way=ter and see if the pin is comming out and switching the micro switch use a small screwdriver to prees the switch in and see if the boiler fires up if it does just replace it will be fine

ps dont forget you will have to isolate the heating with the 2 valves on the boiler and isolate the cold feed in
dont know what ypu mean with the proportion a thing never heard of anything called that on a combi unless you mean the multy function gas valve if you have then it will need resetting by a corgi man as its to do with gas working pressures high and low settings etc
best of luck mick

 

[petkow]

Thanks so much for the reply Mick. I hadn't really ventured that deep yet. The diaphram is not moving so that's what it is. Moreover, pushing the microswitch gets it going though still no hot water as obvously the other part of the valve setup is not doing the diverting. Clever thing this diverter valve! Responsible for both sensing and sending heat to either CH or water. I'm learning!

I will get the unit out tommorow and open up the diaphram housing. The whole diverter valve unit will cost around 70 quid, wheras the diaphram is quite a bit cheaper so looks like I will try that first. Let me see... I may be able to get a cheaper price on that elsewhere. Are they fairly generic or are they specific to boiler make and model?

Anyhow, the other thing that I messed with is obviously the multi function gas valve that you mentioned. Luckily the boiler is working OK for central heating so I may just leave it assuming the diverter valve cures the hot water issue. Is it a big "no-no" to adjust those? Coming from an automotive background I presume I can compare that to carburettor tweaking on a petrol engine?

Thanks again... you're the first person who has assured me I (hopefully) don't need to get a new boiler after all. Couldn't afford it at the mo!

 

[bengasman]

If you can knock a hole in a rad, there has been an enormous amount of corrosion over the years and your system is probably full of sludge, which causes problems with diverters. The sooner you get the muck out, the better.
If you have fiddled with the gasvalve, you must get a CORGI out asap as your boiler would be unsafe.
Most parts are boiler specific, though often not unique, compare car batteries.
Must admit I have never heard of a sime halstead, I know both names but not together.

 

[petkow]

You're probably right about the corrosion though the leak was on one of the pipes going into the radiator. It was knocked quite hard by a bit of furniture and the nut was loosened. That led to a rather slow water loss.

It would definately be best to get the system cleaned out though as you mentioned. I presume this would include a radiator power flush too. Thanks though for all your help and advice. I am a bit worried about this gas valve setting now especially as you say it compromises safety. I presume that is what we are talking about though. It is an electrical reostat type adjustment which is mounted on the front of the main gas solenoid unit. It has a Philips screwdriver slot and is labelled "Proportioning Unit (24V)". I have seen it mentioned by someone else here on DIYnot too though he couldn't figure it out either. I can only assume it is what you guys say it is though, but not 100% sure as there are other tweak screws directly on the solenoid unit a bit further back (and less accessible). The one I adjusted just seems too accessible to a novice like me!

 

[bengasman]

The gasvalve determines how much gas goes through at any time. If the settings are wrong you could get the boiler equivalent of doing 150 in a fiesta, it could go right and it could go badly wrong.

 

[petkow]

Cheers Ben. Will get it checked over. Should I just be asking a CORGI chap to come over to "reset the gas valve"?

By the way...All the automotive analogies are very useful for me. Thanks again.

 

[bengasman]

I always recommend to tell the engineer what the problem is and what has happened but advise against asking to do a certain thing.
Any engineer worth his keep should be able to work out what needs to be done based on the information given about what the problem is.
Even with no info at all you should be able to bring the boiler back up to spec, it just helps if you know what the history is. It gives you a head start and thereby saves some time, which in turn should save you money.

 

[Agile]

Having filled a system with a hosepipe connected to the PRV which had no vent and packed up to leave, the tenant then tells me that a rad was cold at the top and needed bleeding!

Always tell the engineer anything relevant about the history BEFORE he starts work.

But DONT tell me what the fault is as its probably not the case and I always expect to diagnose the problem myself and then I can take responsibility for it!

Tony

 

[ChrisR]

 

[petkow]

Off to the shop down the road who apparently do a kit for 16 squid. Not too bad. I will strip it down ASAP and keep you guys posted... also for the benefit of anyone else wanting to do the same.

p.s. As I have seen a fair few posts elsewhere on DIYnot about this boiler which is the Sime 30/90 (AKA Sime Holsted Combi 30/90), I thought I would post what I have learnt about the Diverter Valve in case anyone does a search in future. The part number is 6102801 which has now been superceded by 6102802. The diverter valve kit (Diaphram and O-rings) is R238. Loads of suppliers stock this kit in abundance.

Thanks again.

 

[petkow]

By the way ChrisR... very useful background graphic you put in there. Have you got that as a GIF/JPG that you can put in a post by itself without the text. (or send by email/PM)?