Comments: I started my strip down of our 28CDi at 9:30 in the morning and finally got it all back together at 9 at night. The problem was it was leaking enough to fill a bucket every couple of hours. I bought the diaphragm rather than the whole valve. When I asked for a pack of O rings and fibre washers the guy in the plumbing shop reckoned only O rings were normally needed for this job but he kindly gave me a couple of fibre washers as well which were needed. Silicone grease can be bought at Maplins.
Draining down the system was tough enough for me because I had no experience of doing this. Have plenty of towels ready. Why water comes out all over the place I have little idea. The filling loop was reasonably simple and the heat exchanger also, but take care to remember the direction/order of everything. When I got down to the diverter valve itself I couldn’t get it off and was wondering if I’d missed something and how much force I was allowed to use. I had to take a trip to the plumbing shop for advice and get my wife on the job who prised it off with one of those mini nail-puller tools. In other words you might have to really put some force in. Unbelievably, the changing of the diaphragm takes about ten minutes. My big mistake (getting lazy) was to assume that the two O rings at the back of the diverter valve (in the case of the boiler itself, yes there is one on the right) wouldn’t need replacing because they hadn’t actually moved.
Getting the thing back together wasn’t too bad but the heat exchanger must go on before the loop otherwise you can’t get access to the big nut. The hardest thing is the bypass pipe which so many other people have mentioned. I found I could get it seated down and the pin in with the diverter valve swung out towards me i.e. that the bypass pipe is done before anything else at all when re-building. I filled the boiler with crossed fingers but reasonably happy, but no, the thing dripped loads. It was then a week of emptying buckets before I had another clear day to tackle it again. A new O ring pack was also needed because I couldn’t be sure the week-old ones would be OK. When I re-did it of course it was much more familiar but for some reason when I put it all back together again there was water puthering out of where the bypass pipe goes in. I was now ready to call the wife back in or smash the boiler with a lump hammer.
The real problem here was that if I needed to take the whole thing apart again just to sort out the bypass pipe then how was I to know whether I needed to renew all the O rings again? Luckily I read the account at the bottom of the home page where the guy suggests taking out the bypass pipe at its other end and with this piece of advice my wife spent about four hours doing this one job without having to take the whole boiler apart. She had to bend the pipe itself to allow it to enter perfectly vertically and says she could tell when the bypass pipe was correctly seated such that the pin will fit easily because it gives a satisfying snap. The job is satisfying when it’s done but, for me, hard work. Good luck and thank-you Mathew.
Admin reply: Well done Pete - if nothing else you deserve an award for perseverence! Regarding the re-use of o-rings, this is perfectly acceptable if the o-rings are not that old as they only start to solidify and permanently deform after having been fitted for a while i.e. after a few months or so. Even then you might be okay but it's arguably a risk not worth taking. ...Mathew
Comments: 1999 FX Coupe(Tiburon). 2.0L with a blown head gasket. but heaps of after market goodies. I want to race it. So I search across the globe for cheap parts.
Wish me luck.
PS: Great info and easy to use site. chEERS, BOYS.
Comments: Damn !!! Boiler keeps tripping on hot water, runs for about 30 secs then fault light goes onto fast flashing,ch runs ok, have changed the dhw sensor and made no difference....any suggestions welcome.........
Comments: The eagle has landed.......!!!!! Took me 6 hours, had to get some more silicon grease and could'nt find the boss white. Glad I left it until the weekend, knew it would take ages. Thanks for all the info-
Comments: Hi I have the same problem with my Worceter 28cdi, going to order the parts tomorrow, the pics look good. I will let you know how I get on, if no contact within 2 days please send out a search party (to include a gas fitter), Thanks, wayne
Comments: I, along with so many others, owe you a big thanks for posting the details of this fix. I have just changed the DV diaphragm on my WB CD26i. The job went well. I too had the problem whereby no water came out when I opened the drain valves; I hadn't bled my rads for ages so I relieved some of the pressure in the system by opening the rad valves and letting some air out. Then I pushed a small screwdriver up the drain valve opening to clear the blockage and the system drained. I'd say the job went very smoothly and I didn't really find any of it too tricky. One thing that no-one had said, and was also totally absent from the manual was that you have to disconnect the pump from the DV - a small point but it had me confused for a while. I took the whole of the DV out to change the diaphragm - found it quite easy that way. Used all new washers/o-rings. Cleaned surfaces and silicon grease all over! No leaks! New diaphragm cost me £7.50 and o-ring pack cost £14. The old diaphragm was totally shot, in exactly the same way as yours. I now have hot water. Thanks again.
Added: December 30, 2011
Submitted by Name: kateland From: Texas
Comments: Was unsure of where the PVC valve was located, found this website from trying to google that. SO glad i found this, its going to be so much help in the future!!
Name: Pete
E-mail: Viewable to admin only
I started my strip down of our 28CDi at 9:30 in the morning and finally got it all back together at 9 at night. The problem was it was leaking enough to fill a bucket every couple of hours. I bought the diaphragm rather than the whole valve. When I asked for a pack of O rings and fibre washers the guy in the plumbing shop reckoned only O rings were normally needed for this job but he kindly gave me a couple of fibre washers as well which were needed. Silicone grease can be bought at Maplins.
Draining down the system was tough enough for me because I had no experience of doing this. Have plenty of towels ready. Why water comes out all over the place I have little idea. The filling loop was reasonably simple and the heat exchanger also, but take care to remember the direction/order of everything. When I got down to the diverter valve itself I couldn’t get it off and was wondering if I’d missed something and how much force I was allowed to use. I had to take a trip to the plumbing shop for advice and get my wife on the job who prised it off with one of those mini nail-puller tools. In other words you might have to really put some force in. Unbelievably, the changing of the diaphragm takes about ten minutes. My big mistake (getting lazy) was to assume that the two O rings at the back of the diverter valve (in the case of the boiler itself, yes there is one on the right) wouldn’t need replacing because they hadn’t actually moved.
Getting the thing back together wasn’t too bad but the heat exchanger must go on before the loop otherwise you can’t get access to the big nut. The hardest thing is the bypass pipe which so many other people have mentioned. I found I could get it seated down and the pin in with the diverter valve swung out towards me i.e. that the bypass pipe is done before anything else at all when re-building. I filled the boiler with crossed fingers but reasonably happy, but no, the thing dripped loads. It was then a week of emptying buckets before I had another clear day to tackle it again. A new O ring pack was also needed because I couldn’t be sure the week-old ones would be OK. When I re-did it of course it was much more familiar but for some reason when I put it all back together again there was water puthering out of where the bypass pipe goes in. I was now ready to call the wife back in or smash the boiler with a lump hammer.
The real problem here was that if I needed to take the whole thing apart again just to sort out the bypass pipe then how was I to know whether I needed to renew all the O rings again? Luckily I read the account at the bottom of the home page where the guy suggests taking out the bypass pipe at its other end and with this piece of advice my wife spent about four hours doing this one job without having to take the whole boiler apart. She had to bend the pipe itself to allow it to enter perfectly vertically and says she could tell when the bypass pipe was correctly seated such that the pin will fit easily because it gives a satisfying snap.
The job is satisfying when it’s done but, for me, hard work. Good luck and thank-you Mathew.
Admin reply: Well done Pete - if nothing else you deserve an award for perseverence!