Heat only boiler with unvented cylinder, which new boiler?

[MElliottUK]

I currently have a heat only boiler connected to a gledhill unvented cylinder. It is currently set up with external expansion vessel on the cylinder (white), various valves, external pump and a small header tank which I think is known as a open vented primary system, this keeps the heating and tank coil loop topped up.

This heat only boiler is now dead, my understanding is that I have a few options:

1. Replace the heat only boiler with another heat only boiler (keeping valves, pump, header).

2. Replace the heat only boiler with a system boiler, I think this means that the pump and small header tank can be removed and the boiler itself will provide a sealed primary system. This sounds good but will require my current system to be slightly reconfigured. The benefits being that the bits removed are old and might need replacing soon anyway.

3. Replace the lot with a good combi, the house is 4 bed 2 bathroom, with unvented cylinder feeding two showers and one bath (2 adults, 2 kids).

Any ideas on what to do, it feels like a have a good system but it's old and the world seems to have moved onto system boilers. I think the setup I have must be a very early unvented system.

It may be also important to note the location of all this stuff:
The boiler is in the garage.
The unvented cylinder, valves and header is in the loft.
Pump is in the first floor airing cupboard, in the location where the original vented hot water tank would have been when the house was built.

What do you think?

[tux850]

During your search it is worth noting that the terminology used is often subject to ambiguity so be careful about different people using different terms in slightly different ways. Also worth noting is that your vented primary circuit design is not related to the fact you have a heat-only boiler - many heat-only boilers can be used with either vented or unvented systems. Converting from vented to unvented is beneficial (removing the header tank as you say) but me mindful that the increased operating pressure could give rise to problems (leaks) that you don't currently have. As for system vs heat-only boilers you've certainly got more choice with the former, and systems boilers will generally have more advanced features given this (and also the fact that with it controlling its own pump there is greater scope for more advanced closed loop control strategies). Personally, I am a fan of heat only boilers as I like things being as simply as they can be, and spreading the components out across the system tends to spread the risk of failure somewhat to and can make any necessary repairs both easier and cheaper. I have yet to go through the motions of planning an eventual replacement for our Ideal Icos heat-only boiler and so am not really in a position to offer recommendations based on first-hand experience.

[Saleen836]

Which new boiler?....... which ever your budget will stretch to that gives the longest warranty, have a google as there are a fair few that come with a 10 year warranty if installed by an accredited installer

[MElliottUK]

Thanks, to clarify I already have an unvented cylinder setup, cold mains feed direct into tank, the small header referred to is for the heating/tank coil circuit. I'm not sure if it's better then leave the configuration as is, move to a system boiler and as a result remove some of the unnecessary ancillaries, or go back to a combi.

The house was reconfigured to an unvented config about 15 years ago.

As for the boiler itself i was going to pick that after understanding my best option.

Thanks for your help.

Heating/Cylinder Coil



Unvented Hot Water Circuit

Edited by MElliottUK on Monday 6th January 21:33