Yet another boiler...

Yes can often be repaired cheaply from used parts on eBay?

Update: decided against W-B due to ally HX. Filled in forms on Vaillant and Viessmann sites, each responded with the same preferred installer in the local town. Had a call, long chat, having a Vaillant ecoTEC Plus 825 fitted tomorrow. Temperature in most of house is now about 13C - I need that boiler! I went with Vaillant as all the parts look easy to get at; Viessmann and WB don't.

Thanks for all the help and advice.

Yup, modern Vaillant boilers seem very well laid out internally - pretty much everything is fairly easy to get to. (slightly less so on the combi perhaps (due to the extra PHE etc) - but even then not bad)

Ironically (given the comment on Ali HX), in the ten years I have had it, the only bit of my 624 that has gone wrong and needed replacement was the main Hx which sprang a slow internal leak! :-)

Laying things out purely for easy servicing may not be the best way in any case. Unless you reckon lots of bits will need replacing often.

For example, things which may have a shorter life with heat may well last longer if sited in the coolest place - even although that isn't the most accessible.

Of course those who make a living from fixing boilers are going to recommend the one which gives them the best living. So lots of easy to do repairs.

Not if (or when) the sale of gas boilers is banned, which seems to be the intention of all the major political parties (or was prior to the invasion of Ukraine)

I can't see any justification laying stuff out so as to make it hard to service, unless it is the only way not to compromise its performance.

In a boiler that would only really apply to the electronics, which most seem to locate at the bottom, as far away from hot stuff as you can get anyway.

Sounds like a load of tosh to me.

According to Which? most reliable brand is WB, closely followed by Vaillant, distantly followed by everything else. What did Mr. Gas recommend?

The firm does all sorts arates Viessmann as marginally ahead of Vaillant. The fitters prefer Vaillant for installation and servicing.

Boiler and filter have just been delivered by another fitter, ahead of the actual fitter turning up (he has about 20 miles, cross-country, on icy roads). Useful info on rads: Stelrad, Kartell, then the others, decreasing in quality. Rads are thinner material than they used to be, so quality is important.

Well, I was told that he was in the same county - he's from Brum! Had an apologetic call to say that he'd had trouble with his van and could he come tomorrow at 07:30. Also offered the first service at about 40% off as compensation, so not all bad.

Not as important as flushing after installation and using the correct amount of inhibitor (and checking it regularly, which few people do)

It is well worth flushing before you install the new boiler - last thing you want to do is flush crap into the new Hx!

Fitting a magnetic cyclone filter on the return to the new boiler is also handy as an additional line of defence)

I took all my rads into the garden, mounted them in my B&D workmate and blasted the crap out with the hosepipe. We have amazing pressure and throughput from the mains where I am.

Getting the residual red gunge out of the copper pipework was then easy.

Also discovered that the original CH installer (1976) never bothered to clean off the flux from any soldered joints so a few of them them were showing quite obvious green 'corrosion' (all hidden under the horsehair pipe insulation and under floorboards.

Also a mild steel round nail 'temporarily' supporting a 90 degree bend in the 22mm pipes going to the bathroom so that every heat cycling of the hot pipe rubbed it against the pipe. Caught that just in time over 15 years ago when I had that part of the floor up for another reason.

All the joist hangers fitted with 4 inch round nails bashed half to 2/3rd of the way in and bent over.

The system will have a chemical flush before the boiler is installed.. I suppose that it'll have another one after the new rads are fitted.

There was a magnetic and mesh filter with the boiler. It's a 'W' - Williams & Co. 304 st. st. mesh and a 'Diverting Block', whatever that is, so that it doesn't stop the flow even when the filter is covered. It's quite big and I don't know where the hell it'll go.

Quite. So do you choose the best boiler, or the one which suits the fitter best? A decent boiler isn't going to need regular repairs anyway.

Having fitted my Viessmann myself, not sure how they could have made it easier to install. All the pipes come out the bottom, same as most. Of course if you replace your boiler with an identical one, it is likely to be easier. I went from an ancient cast iron floor stander, so altering the pipework was bound to be needed.

Indeed - most are pretty straight forward to fit these days. It is the internal layout of stuff that makes much of the difference for maintenance. For example, there are still plenty system boilers and combis that put the expansion vessel right at the back, meaning to replace it you need to dismantle a substantial amount of the boiler including gas carrying parts.

On others like the Vaillant models and a number of others, it is located to the side, and can be disconnected and replaced with one water pipe union, and a couple of screws.

Yup same here, I went from a floor standing cast iron lump Ideal Mexico, vented system, vented hot water, to sealed system boiler, with unvented primary circuit, and unvented cylinder, plus a massive update in controls and zoning. Took best part of a fortnight to get it all complete and working the way I wanted!

On mine, the pump and diverter valve were situated at the hot water cylinder - on the other side of the room from the original BE boiler.

Managed to re-use most of the pipework when going to a system boiler. But had to add a cold water feed to the bathroom (where they are installed) so took the opportunity to change the cold to the basin to potable, rather than from the tank.

I've not found anything on the Viessmann to be a problem as regards accessibility. Mainly because nothing inaccessible has needed attention. Yet.

It's now installed and working. A few snags, one involving unwanted water :-~. I did quite a lot of the running-around bits to open and close valves and when two people made it a lot easier. Flushed with a chemical and inhibitor added - don't know what sort and don't know how to check it. Leak in gas meter cabinet, old meter removed, Cadent turned up and put on a new one; also left a CO2 monitor - not sure that I need it with this boiler(?) Tried to get two monitors but he had only one on the van. New meter is digital (same as old one) but in m^3, so my spreadsheet will need a tweak. Lots of clearing up. He was going to do it, but as he came from Brum! I was happy to let him get home. I am disposing of the waste as his van is in the garage and his car wasn't very big. Seems to be working OK, very quiet, controls are a PITA cf. the old one but more flexible. Got flow set to 55C.