New central heating system, advice please

[Fab41]

We currently have an old Rayburn nouvelle which runs CH, hot water and cooking. We have an immersion tank in airing cupboard and a header tank in the loft room.

Heating engineer who services the Rayburn said it is possible to separate the boiler/cooker and leave it as cooker only. We could then install a separate boiler which would be far more efficient. We are about to have a new water main installed to address very low flow on a shared connection.

Has anyone else done anything similar? We want to get rid of the header tank to have more space in loft room, but not sure what to be looking for or asking plumbers. Any advice welcome, thanks

how many people live in the house? How many bathrooms and showers?

What age and size is the house?

Do you know what size the old and the new water pipes will be? The old one might be 1/2" lead, and the new one will be blue plastic, possibly 20mm but preferably bigger.

How big is the loft tank you mention?

How big is the cylinder, what colour, and have you got room for a bigger one?

Ok, three people in house. One bath, two showers (one shower is electric), three loos.
House is 3 bedroom, semi detached, 1937. One bedroom is in attic, both bath and showers are on first floor.
Don't know what size old pipe is, not lead but old and hard water, so clogged up. At the moment, if our neighbour starts her washing machine, the electric shower stops. Ditto if we flush toilet or run a tap. New water pipe will be 32mm from main, then 25mm into each house.

Loft tank is boxed in, so can't see what size it actually is, but must be the size of a bathtub judging by the space taken up.

Cylinder is copper tank with old insulating jacket, thermostat is knackered as water is always boiling hot. Old mechanical timer in airing cupboard. We could potentially have a larger cylinder.

Thank you!

No thermostatic valves on radiators. Need a radiator in loft room.

I would strongly recommend that you get an unvented (pressurised) cylinder such as a Megaflo (tm) or other brand, and conventional or system boiler. Conventional is the simplest type so has less to go wrong. Get your heating engineer to measure and test water flow and pressure with the new pipes. 12 litres per minute is the lowest acceptable, 20 litres would be great.

You will also need larger pipes and fullbore stopcocks right up to the new cylinder, and preferably on to the bath tap, to avoid constricting your good flow.

If you are on gas, Worcester-Bosh and Vaillant are two good brands with lots of experienced menders. I have a Viessman which is also very good with stainless steel parts that last well, but they are not sold in such vast numbers in the UK, and don't go wrong often, so if you are outside a town, you need to verify there is an experienced Approved Installer locally.

If you are on oil, ask your friends, neighbours and serviceman for recommendations.

Thanks, we are on gas, so will look into those options.
Would a conventional system not need a header tank?

a "conventional" boiler (not pressurised) uses a small tank or cistern, about 2ftx1ftx1ft, usually in the loft, to keep the radiators topped up and to absorb the expansion when the water in the radiators and boilers heats up. The alternative, in a system boiler, is that you pressurise the boilers and radiator, and have an expansion vessel which, like a balloon, contains some air to compress when the water expands. The tank is more old fashioned, and can get dirty, but is simpler. You will have heard of people speaking of losing pressure, or the pressure going too high when the expansion vessel goes wrong.

The little feed and expansion tank doesn't usually make a noise, as water does not flow into it unless there is a leak, or you have drained the system and need to refill it. It will usually last about 50 years. This water is quite separate from, and does not mix with, the tap water.

I am quite old fashioned and like simplicity, but opinions differ.