Keston Celsius 25 fitting

[Paul Roman]

After years of lurking and reading the all the useful info (thanks all espically Ed and John) I've finally taken delivery of my Keston boiler, rads and assorted bits. Most of the pipework I installed a couple of years ago while I had the boards up re-wiring, re-plumbing, etc.

However there are some details I'm still need to clarify. In particular the instructions for the Sealed System Kit lack detail and seem to contradict Section 2.7.2 of the boiler instructions.

1. The short section of 22mm pipe with the 15mm branch terminated by a male threaded fitting I assume should be fitted to the return and the branch connected to the expansion vessel.

1. The other short section of 22mm pipe with a 15mm branch terminated by a fitting with a red knob and a female threaded outlet I assume is the 3 bar safety valve. This should be fitted to the flow? Would it be acceptable to connect the safety valve outlet to the condensate drain? Or does it have to be terminated outside?

2. The instructions are silent on where to connect the pressure gauge. There is a blanking plug on the return fitting (Part 120, Diagram

5.7.2 'Waterway, Condensate & Flue Assembly', Page 34 Installation Instructions) that appears to be in the right place and size.

1. Does it matter whether the filling loop is connected to the flow or return?

I've a fair idea what most of the answers should be but I'd just like confirmation that I'm right.

I will of course be getting somebody in to commision the system so if anybody knows a good Corgi engineer in North London (Tottenham) please let me know. (Do you cover this area, Ed?)

Thanks

Paul

[Andrew Gabriel]

Yes.

I ignored most of their pipework which came with the system unit and made up my own. One of the purposes of the extra box, as far as I was concerned, was to hide all the pipework, so I didn't want it exiting the box at the bottom. I cut a large hole in the side of the cover, and routed the pipework out through that and through the adjacent wall. I wish the extra box had got a bottom on it though -- my boiler is mounted quite high up and you can see into the bottom of the system kit box.

If I were doing it again, I also would not use the gas valve they supplied, but would get a full bore one, or fit one before the pipe reduces to 15mm. Their 15mm gas valve has quite a restricted bore, which seems rather silly for a ~25kW boiler. (Also, I ended up with two of them -- I think the boiler came with one and the system kit came with another one. Fitted the second one on the hob which hadn't previously had a gas valve.)

No - condensate drain should be plastic, and I really wouldn't want to use a plastic pipe for the pressure relief pipe which could be carrying very hot steam.

Pretty sure (don't have instruction on me).

Don't have the instructions, but what you say sounds right. (Actually, nothing anywhere in any spec I had ever indicated the system kit would contain a pressure guage, although I'm glad it did.)

Some other tips...

Make sure you have someone strong with you when you lift the boiler onto the wall -- it's bloody heavy. I did manage it by myself, but I wouldn't try that again. You'll need strong ladder(s) too.

Make really sure the flue is watertight. The exhaust spigot on mine wasn't (their muPVC to stainless steel join wasn't waterproof, and neither was the exhaust gasket, because the mounting holes in it were too small and didn't clear the rivited bosses). When you've got it all plumbed in, I suggest you set the garden host to a very small trickle and push it into the end of the flue. Leave it running for a good 10 minutes or much longer, and check no water is leaking out of anywhere in the boiler, flue pipework, or condensate pipework. (Make sure it is running out and not filling the combustion chamber!) The real condensate is corrosive and will do considerable damage quite quickly if it does leak.

Don't assume there are no leaks in the boiler pipework. I included it in a circuit when pressure testing, and did have a leak. Having checked and ruled out all my joins, I tested all the joins inside the boiler, and the drain valve was leaking where it screwed into the elbow casting.

If Ed can't, Keston will do it for £120 (can't remember if that includes VAT, probably not).

[IMM]

The high pressure relief pipe should be terminated outside. It has to be copper. It doesn't require a sleeve through the wall. It has to terminate at floor level and an elbow turning into the wall. If super hot water is emitted it will only hit the wall at low level. In the days when there was no regs, some of these could squirt out into people's faces.

You can terminate say onto a flat roof. Once again it must have an elbow turning the output into the wall.