Have to replace combi boiler - which one?

[Marnhullman]

I have a small cottage with 8 rads (9 if a double is counted as two) with a Grant 90 combi boiler that has given up the ghost and has to be replaced according to a well known and respected local heating engineer.

When the boiler worked we only got a very slow flow from the domestic hot water, due probably to furring up, so a new combi should be better but still not great I imagine. However, as the property is only used at weekends we can probably put up with that as the additional cost of a cylinder type boiler will probably be prohibitive?

The heating engineer has said that the existing boiler is oversized and we could get away with a 70,000 btu boiler but it's possible, although unlikely, that we may extend the house and add four additional rads and an en suite bathroom. So would a 70,000 btu boiler be sufficient for that?

The current boiler is free standing and I would like to free up the space and install a toilet in the room in which it is housed so the options are to have an external boiler hung on the outside wall, but then we lose the heat generated by it which seems a waste or we could have an internal wall hung unit but I fear it may take too much space.

Does anyone have experience of external boilers i.e. do they rust up quickly etc? Also how good/bad are new combi boilers and do forum members have favourite brands? Should I just pay up and have a cylinder type boiler?

Thanks for any advice.

 

[wilhelm]

how old is it?
i cant believe its not possible to fix. as its a w/e place, id drain down, rip it apart slow time, and see what the prob is. and if ididnt know, id contact grant tech help.

 

[oilman]

wilhelm is right, this can be fixed. Most "heating engineers" who work with oil, can't or won't fix combies. There's nothing on a Grant than can't be fixed apart from a leaking water jacket. (Even that can be fixed if you really want to and you don't want a guarantee).

As for 70000 or 90000, this can be done near enough on the same boiler by normal adjustments and setting-up.

If your water pipes from the boiler aren't 28mm or larger, then even with a 70000 can't get the heat away down the pipes fast enough. The high power output of combies is to give the DHW performance.

I don't recommend combies except rarely, but you have one, and making it work is the cheapest thing to do. Add a siliphos water conditioner and you shouldn't have too much trouble.

Unless your HE can give me a verbal going over and convince me I'm wrong, respect is not a word I'd use.

 

[Marnhullman]

Wilhelm/Oilman

Thanks for the advice. The boiler is leaking from underneath but I can't see from where so possibly it's the water jacket? I have experience of amateur plumbing but nothing with boilers but am willing to give it a go if it's fairly straightforward. Do I just dive in and start unscrewing and unbolting components until I find the problem or can I disconnect the boiler and pull it out so that I can take a look from the back in case the leak is from there?

If it is the water jacket leaking can I replace it or if not how can it be repaired?

Thanks

 

[wilhelm]

chances are if its dirty/brown water the jacket has gone.
but, i always check all water connections on a boiler thoroughly, in case it isnt thereby ensuring i dont look a complete **** when its not the water jacket