combi or open vent?

[thirdtimelucky]

I have an ageing Potterton floor standing boiler which I installed 16 years ago and it has never faulted. I am considering the time when it will need replacing and what to replace it with.

There are only two of us and the property is a bungalow with one bathroom and one kitchen sink and nine Radiators.

I would think that the logical replacement would be a combi, however, I have several reservations and your comments would be appreciated.
(a) The higher pressure is more likely to find/cause leaks and as all the floors are covered in solid wood laminate the cost and work of lifting if leaks occur will be expensive.
(b) The cost of annual maintenance on the boiler will be more expensive than open vent boiler
(c) They are more prone to problems than an open vent boiler
(d) If it fails (especially in winter) we will have no access to hot water even in the bathroom.

I did consider a power shower as a back-up but as our bathroom has been refurbished and tiled floor to ceiling that would not be an option.

Do you think my worries re a combi are reasonable or groundless?

(My kids have a combi in their homes and both have had various niggly problems that have left them without hot water and expensive call out costs.

 

[OwainDIYer]

You appear to be confusing combi boilers, which heat water instantaneously, with sealed radiator circuit systems.

Advantages of a sealed radiator circuit include no heating header tank in the loft to overflow, freeze, or draw air into the system, and if there is a leak from the radiators then the volume of the water is limited.

 

[ctp]

If you are worried about pressuring your rads install an open vented combi, but your hot water system will be at mains pressure as with any combi.

 

[Galoka]

I fitted a combi in our old house, as that enabled us to get rid of the airing cupboard, which gave us more space in the small bathroom which was welcome. Overall it was a good choice and the shower was good. Though bath filling was pants.

But we have since moved house,and have got a stored, vented HW system again. And overall I prefer that now that space isn't such an issue. I like having a tank that has a backup source of heating the hot water. I like having the warm airing cupboard (though that could be achieved with a low wattage tube heater).

Occasionally when we have a house full of guests, the unlimited HW from a combi would be useful, but in normal day to day use, the stored HW provision is fine for us.

OK, we aren't looking to change it anyway, I'm perfectly happy with our nice old simple Ideal Mexico. But even we were I'd not go for a combi. Though I did like having a pressurised heating circuit.

(did ponder a mains unvented cylinder here, but our mains supply isn't that great)