Combi boiler expansion vessels

[Alfie25]

As part of the overhaul, I will be getting 6 radiators replaced. I already had 2 replaced recently (swapped from singles to doubles) so there's going to be a lot more water/radiator area to heat, but that shouldn't be a problem for a more powerful boiler. Upstairs is particularly under specced, with e.g. a tiny 500 x 700 single panel non convector in a room 3 x 3 metres square.

I will of course, as you advise Tony, be asking the RGI to advise. I was just thinking they would prefer the householder to have some idea of what they want/need.

In terms of the conflict, I'm sure I'd read somewhere on here that the advice was that it's more efficient to set the boiler high so the rads get hotter quicker, rather than set the boiler lower and them taking much longer to heat up.

 

[Agile]

In terms of the conflict, I'm sure I'd read somewhere on here that the advice was that it's more efficient to set the boiler high so the rads get hotter quicker, rather than set the boiler lower and them taking much longer to heat up.

Anyone can post advice here!

Even professionals can have differing views too. Look at the MPs in our Government !

The best way to heat a system quickly is to have a lot of POWER available to heat the cold rads quickly. But their heat output is not massively changed ( about 20% ) by increasing the flow temp to 80 C rather than 70 C. But once warmed up the boiler efficiency is about 10% lower if its run like that.

Intelligent controls will help with this but to get the best efficiency and comfort you need weather compensation!

Tony

 

[Alfie25]

I'm from the school of keep it simple, stupid. I don't doubt weather compensators have their fans (my friends dad likes his, but i think it's more for bragging rights in the village pub) but I subscribe to the more complicated a system is, the more there is to go wrong.

I know combis have pitfalls and to be honest I like many aspects of my old school fully pumped system with a cylinder full of hot water almost always available, but this does seem to be yesterday's technology, plus my system in its current state is riddled with problems. I'm aware of megalflows too, but dont fancy one in the house and my garage is not adjoining the house unfortunately. Plus, more to go wrong.

Cheers for the advice on here, it's all good to know. Next step is to get a couple of quotes from RGIs, although I'm sure their time to discuss the ins and outs of my new system will (rightfully) be quite limited until I've agreed to contract them. One last question for now... one of the main reasons I'm getting the system overhauled is the banging pipes, mostly upstairs. They're tight on the floorboards and making them lift in some cases. I'm wanting them all either replaced or re-clipped/dampened. And I want it all in copper as I don't trust plastic. Is this a request too far? Cost is not really a problem as it'll be money well spent for not getting woken up all night with pipes creaking and banging!

 

[Dan Robinson]

Combi's are really no more complicated than a standard boiler and S-Plan.

An Intergas is even simpler in terms of things to go wrong.

The downside is that if the boiler failed there is no immersion to fall back on.

Weather compensation is just a single extra sensor giving readings to the boiler circuit board - 95% of all new boilers have the software already on the board....

So nothing more to go wrong.

A weather compensated Intergas Combi is as simple as a modern highly efficient heating and hot water system can get.

Can even leave the heating open vented with a header tank in the loft for the rads if you are paranoid about the old system's integrity.

 

[Alfie25]

I've got no immersion heater anyway! From speaking to the last owner, British Gas replaced the HW cylinder, but didn't refit the immersion, so I've just got a lovely blanking plug in the top.

Dan, is your last comment about the integrity referring to the pressure that combis run at vs my old system boiler (and pump)? I didn't think a combi could be run on an open vent for the radiators, but I'm learning all the while.