Which boiler do I want?

[spikeyhead]

I live in an old stone built house, reasonably well insulated and adequately heated by an old vented Gloworm boiler which still works, but it at least 20 years old and I'd rather replace it this summer than waiting for it to go wrong in the depths of winter. The existing boiler is on the wall of the downstairs cloakroom with a 22mm gas pipe going to it. There's a larger than usual hot water tank in the loft which has immersion heaters that aren't working.

Mains water pressure is poor and hot water flow rates aren't great especially downstairs aren't great.

What should I have installed? looking for best reliability from the boiler and better flow from hot water taps.

[mrmistoffelees]

On pretty much zero knowledge of your requirements, system plus unvented cylinder?

[spikeyhead]

What other information can I provide to help the decision?

[mrmistoffelees]

How many radiators/rough size of the property, what your usage is, how many bathrooms/how many showers, how many people living there and what the rough usage is.

For instance, if you've got a five bed house with 17 radiators, one person living there that showers once a week then a combi may well do the job.

If you've got a two bedroom house that's been converted into an HMO with 8 people living there and 3 bathrooms and they all shower for an hour a day then a combi is going to be horrible.

Logically you'd usually put the combi in the two bedroom and maybe the system in the bigger, but usage patterns can change how you approach things.

Edited by mrmistoffelees on Tuesday 15th April 21:42

[spikeyhead]

Four large bed house, two of us there, two showers, 12 radiators, which are mostly too small. Walls are stone, 18 to 24"" thick, which if the place ever gets cold and wet take an age to heat up.

There are times when we both want a shower at the same time.

I also want longevity and a trouble free system.

[megaphone]

If you have low mains water pressure/flow then a combi is likely a none starter. You could get the flow tested.

Ditto an unvented 'megaflow' system, although a pump could be installed.

If there is nothing wrong with your current set-up, and meets your needs, then just get the boiler replaced and get the immersion heaters working etc.

Or just leave it alone, many of the older boilers are better made and more reliable than the new ones.

[Turtle Shed]

spikeyhead said:

I live in an old stone built house, reasonably well insulated and adequately heated by an old vented Gloworm boiler which still works, but it at least 20 years old and I'd rather replace it this summer than waiting for it to go wrong in the depths of winter. The existing boiler is on the wall of the downstairs cloakroom with a 22mm gas pipe going to it. There's a larger than usual hot water tank in the loft which has immersion heaters that aren't working.

Mains water pressure is poor and hot water flow rates aren't great especially downstairs aren't great.

What should I have installed? looking for best reliability from the boiler and better flow from hot water taps.

Your hot water pressure is done purely by gravity, a small-ish cold tank (high up in the loft) feeds the hot tank (lower down) and gravity makes the water 'fall' to your taps when opened.

I am not a plumber, but lower hot water pressure downstairs suggests a plumbing problem of some sort. Because of the gravity thing the hot water pressure downstairs should be better than upstairs. My guess is that you have long pipe runs, of 15mm pipe, with a fair few joints/elbow bends which can/will compromise pressure.

I'd get the immersion heaters fixed (hot water backup for if the boiler fails) and consider moving to a cheap overnight tariff as an option for heating water on a timer. (Saves wear and tear on the boiler). I'd get a plumber round to assess why the hot water pressure is poor - you might be able to sort this with 22mm pipe and a better layout.

As to replacing the boiler, if it's working I'd stick with it. For reference we have a Trianco oil boiler that was installed in 1992 (by previous owners) and it is still going just fine. I'll replace if it ever needs an expensive repair, or if parts aren't available for a repair, but I see no reason to spend around £4k replacing something that works.

[Domski86]

Can you confirm whether the mains pressure is actually low or if the current pressure seems low because of the gravity fed system? Usually there is at least one cold tap in the house fed directly from near the stop cock which might give you a better idea of actual pressure.

Everyone saying stick with the old has clearly never had a decent modern heating system. Old gravity fed system boiler type systems are utter ste. You just get used to it. The difference any type of modern system makes on central heating system warm up times and overall ease of use is huge.

Your use case would suggest an unvented cylinder type system (assuming water pressure is ok) over a combi. Wouldn't rule out a heat pump as long as you can find a competent (Heat Geek) installer. It's a similar set up to an unvented system in the sense there's a big pressurized tank it's just the main unit would be externally mounted rather than internally.