Advice - updating a CH system

[DavidM]

My existing CH boiler is now over 35 years old and I'm looking at replacing it and maybe updating the system.

It is gas fired, open vented, fully pumped with a fairly new indirect HW storage cylinder. The timer is digital, providing separate control of the HW and CH, and the room stat is a new digital programmable unit. There's a total of 10 radiators, varying between 3 and 35 years old, most with TRVs. The boiler is located in an old chimney breast in the middle of the house with a conventional flue up the old chimney, rising about 36 feet up (a replacement boiler will probably have to go in a quite different location - no access for a balanced flue).

The house is a Victorian semi, with kitchen, dining room, large lounge and hallway on the ground floor, 3 bedrooms, toilet, bathroom and landing on the first floor, and bedroom, study and shower room in a loft conversion on the second floor. The walls are all 9 inch solid.

I want to do some of the work myself, particularly replacing radiators where necessary, in a phased approach as rooms are redecorated, and any work associated with removing the old boiler (gas work excepted). I have in mind a Worcester Bosch boiler (not a particular model) and either an open vented, or sealed system if the existing pipework is suitable. I don't want a combi. Having had a couple of "silly" estimates for just supplying and fitting a new boiler, including British Gas and an independent CH installer, the approach I'm now considering is to commission a CH engineer to inspect the existing system and then produce a design for updating it, including a replacement boiler. Based on this design get estimates and then someone in to do the bits I can't do (like install the new boiler), with me doing any prep work, maybe the electrics, and "labouring", followed by me doing any further updating (eg new rads). An option might be for me to source the boiler. I'd certainly want the boiler installation properly certified.

I'd be grateful for any advice on:

1. Is this a sensible, viable approach?
2. Based on the info given what might a CH engineer charge for the design bit of the work?
3. Any recommendations on CH engineers in the mid Herts area (I'm in St Albans), a) to do the design, b) to undertake the work.

Apologies for the long winded post, just trying to give enough information so people can make sensible comment.

Thanks, David (remove _notme from email address)

[The Natural Philosopher]

Why should the new boiler have to be a balanced flue?

Hmm. worth comparing the cost of a new boiler to dry lining the outer walls.

Seems so.

Too much ;-)

[Jim Alexander]

No. Its a "silly price plus" approach. What you call "supply and fit" actually involves substantial work in relocating pipework and controls, bringing controls up to date, knocking through 9 inch walls for the flue, removing and taking away a heavy cast iron boiler, not forgetting the obligatory powerflushing of all these old radiators.

Anyway you didn't say what "silly" was but after enough quotes its the market price unfortunately.

Jim A

[John Stumbles]

You may find some of the articles here helpful. (If not perhaps you can suggest what you'd find useful - you can reply here or on specific articles' talk/discussion pages.)

Designing the system is not something I'd usually do as a specific paid job (and I guess that would go for most small installers). I'd probably discuss the design with you verbally and if you wanted me to do some of the work (like the boiler installation) I'd do heat loss calcs etc as required. You could do these yourself easily enough. An installer can probably get a boiler cheaper than you can so you'd be advised to get yours to do that.

[TheScullster]

"DavidM" wrote

I would have reservations about a "phased approach" on a system of this age! At some point (unless you have been meticulous about system cleanliness, inhibitor etc) you need to clean out the entire system. Whilst there are advocates of power flushing in this NG, most think it is overpriced and not necessarily totally effective - depends on system layout, pipe routing etc to some extent. If you can arrange at some point before the new boiler is fitted to have all rads off, I would suggest that cleaning out pipe work with mains pressure water would be as effective as power flushing if not more so. Blank off vent/feed pipes. Connect mains water. Hook up hose to each rad valve in turn and blast water through each valve and wherever else you can. Put some kind of filter on discharge end of hose to catch the big bits for examination (I use net curtain material but something finer would be better). This method should give a degree of confidence in the internal state of pipe-work. However, there are certain points which attract serious crud usually around the point where vent and feed pipes join the heating circuit. Would be well worth checking these for obstructions.

Phil

[TheScullster]

"TheScullster" wrote

Forgot to add - flush out radiators with mains water as well before re-fitting. For big radiators this needs 2 people as it is important to invert them frequently while flushing and to shake them to get crud into suspension.

Phil

[DavidM]

Most seem to, but that's what a heating engineer would advise me on anyway.

At 35 years old, and with growing piles of rust on the floor at the back each year I "spring clean" it, I suspect that the old boiler won't last much longer anyway.

[DavidM]

Pump and valves will need renewing, but then these are all adjacent to the boiler. Timer and room stat are new anyway, and renewing a cylinder stat is trivial!. Knocking through a 9" wall...? The plumber at my sons house did it in 20 mins with a core drill! Anyway, if the boiler goes in the loft (an option) the vent can go out the roof.

£4500 just to replace the boiler, pump and valves, and relocating it to an outside wall about 6ft away from present location. That equates to about £3500 just for labour. Even at £40/hour thats over 10 days work.....NO WAY!

[DavidM]

Thanks.

Whoever does the design is probably in the best position to give a competitive quote, so its quite likely they would get the job. Happy for installer to supply boiler, at a reasonable margin.

[DavidM]

Point taken, with a new boiler the system would need to be flushed first, otherwise boiler warranty probably void. Last year I did fill it with flushing additive and run it for a couple of weeks, then refilled with inhibitor, but it probably needs a good "shake up".

[Mike Tomlinson]

In article , DavidM writes

That's just the engineer's way of telling you he doesn't want the work. He's probably reckoned that 35-year-old pipework and rads are going to cause too much trouble even with power flushing and strainers, not to mention the likelihood of leaks springing out all over the place when the system is converted to pressurised.

[Lobster]

Yes I can speak from experience there!! Had exactly that happen to me at home once: both my two oldest rads experienced mid-panel bursts...

David

[DavidM]

Fair enough, but why not just explain that to me. Surely that's more professional, and I can't (wouldn't try) force him to take on the work!

Leaks - is it possible to do a pressure hold up test on the system, like you do on a gas installation (might have to block up the feed and vent but that's easily done). So maybe I should just stick with a vented system.

David.

[John Stumbles]

Yes. Cap off anything vulnerable and fill up to mains pressure (or stop at about 3-4 bar if your mains is much higher than that) with a pressure gauge (£5 plus a few pence adapters from BES or silly money elsewhere) attached. Bleed so there's not too much air buffering it. Leave for a few hours or overnight - should be no major drop.

[Lobster]

Because, Grasshopper, it is a Fundamental Truth that no tradesman in the history of the universe has ever told a customer they don't want work.

They will give you a piss-off price (as yours has done); they will tell you that they're busy until 2 years next Whitsun; they will ignore all your desperate phone calls and messages for weeks - anything to avoid saying the words "sorry, no can do".

David

[Lurch]

On Sat, 31 Mar 2007 17:13:33 GMT, Lobster mused:

I did once, they told me it wasn't good enough and I was doing the work whether I liked it or not.

Works for me. ;)

[Ed Sirett]

In my ignorance I have been known to use those words.

It is amazing the anger they generate, it is better to use them as early as possible but probably simpler to not use them at all.

[raden]

In message , DavidM writes

Now there's an optimistic statement if ever I heard one

[raden]

In message , Mike Tomlinson writes

Would you like to replace the word "engineer" with "fitter" there, please ?

[Alang]

Not another pillock who thinks only someone with a benny badge is an engineer.