What Output Do I Need

[DenG1]

I need to replace my back boiler. Have had a few quotes from local heating engineers. Boiler is being re-sited in the loft, have been advised against fully pressured system in case of leaks in old pipes. Two have suggested Vaillant Ecotec range but one has suggested the 418 and one the 428 which has a higher output.

I have a fully pumped system with F and E tank, and 6 radiators.

Any advice gratefully received

 

[Deleted member 105431]

the ecotecplus 418 or the glow worm ultracom 18hxi (which? magazine best buy award) would be adequate, as you only have 6 rads and a cylinder. I would be concerned about an open vented boiler in the loft as there is a minimum distance between the bottom of the f&e tank and the boiler. I would convert it to a sealed system and deal with any leaks IF they arise.

 

[D_Hailsham]

I need to replace my back boiler. ...Boiler is being re-sited in the loft, have been advised against fully pressured system in case of leaks in old pipes.

I have a fully pumped system with F and E tank, and 6 radiators.

From the boilers suggested, I take it you want to keep your current hot water cylinder and not install a combi.

The Recommended Boiler Size Calculator on the Sedbuk web site will tell you what size boiler you need. I doubt if it will be even 15kW!

 

[mickyg]

What output is your current back boiler? do the rads all heat up in sufficient time? If the answer is yes, then there's very little reason for your new boiler to be higher than your exisiting one. recommending 28kw on 6 rads is idiotic.

 

[DenG1]

Thanks for responding. Im dreaming boilers and heating systems at the moment. I've had 3 local heating engineers and British Gas quote for me. Only one has suggested sealed system owing to age of the house and not knowing the condition of the pipes. All have said I need to raise the f and e tank in the loft to as high as possible.

Is it right you can get something to stop air being sucked into the system.

I would prefer it in the loft as its least disruption to the rest of the house (allegedly!)

Im not sure of the output of the back boiler, I didnt pay that much attention when the British Gas engineer was working it out to check the size of my airbrick for ventilation, I think it was high teens or low 20's. The radiators all heat up ok.

Im no expert but the few people I know who have combi's have had problems, I appreciate this could be down to the installer or a cheap boiler, but I would have been up the proverbial creek without a paddle these last few weeks without my water tank! We will be having a new better insulated tank fitted at the same time.

Thanks again for the advice.

 

[JohnD]

I'm just a householder

a boiler in the loft is relatively inconvenient and inaccessible. Service people may be unwilling to clamber up a typical rickety ladder with poor lighting and insecure flooring with no safety handrail. It will also be awkward to carry the boiler up there and you will need a new gas and electricity supply as well as the water pipes.

a new boiler will only be about the size of a small kitchen wall cabinet, and will be much easier to look at and adjust downstairs. I bet if you rearrange your collection of coffee mugs and jam jars you will be able to put it in the kitchen or somewhere.

 

[D_Hailsham]

I'm not sure of the output of the back boiler ... The radiators all heat up OK.

The back boiler may have been oversized when it was installed, as that was the tendency when they were in vogue, so it is no guide to what you really need. If you have only 6 radiators and the tank you will probably need only a 10-12kW boiler.

But, as I suggested earlier, you can find out what size you need by using the Recommended Boiler Size Calculator on the Sedbuk web site. It is not complicated to use at it is intended for the non-expert. It will save you a lot of time and endless argument with contractors. Give it a go and come back here with your answer.

As for the height of the F/E tank, this will depend a bit on what the boiler mfrs specify; but if you work on the basis that you will need 2 metres from the top of the boiler to the top of the bend in the vent pipe, you should be OK.

 

[gas4you]

I would agree with DM. I always fit a system boiler where possible. I would expect you to need a Ecotec Plus 615.

 

[Norcon]

Agree with JohnD. Very good points.
How many among you guys that are servicing boilers would like to clamber into someones loft space with your tool cases?

 

[The Baker]

Agree with JohnD. Very good points.
How many among you guys that are servicing boilers would like to clamber into someones loft space with your tool cases?

As a 61 year old youngster I still pop in to the loft with out a second thought,

however I do need a ladder,

Jumping up to grasp the edge of the loft opening and getting up by pure agility is behond me now..

But do take your point.

Tim

PS have you considered having your BBU repaired? Which model is it?

 

[Norcon]

Yeah ladders are useful.
My ole pops a while back ventured unto the garage roof using the ladder and it slipped from under him leaving him clinging to the side.
Somehow he managed to haul himself up and was stranded there for 4 hours until the postman arrived.

 

[muggles]

All have said I need to raise the f and e tank in the loft to as high as possible

That's all very well but the base of your cold water storage cistern (tank) that feeds your hot water cylinder and any low pressure taps MUST be at least level with, and preferably above, the base of the F+E. That makes the F+E about two foot down from the apex of the roof just to account for the CWSC, assuming you raise the CWSC into the apex

I would prefer it in the loft as its least disruption to the rest of the house (allegedly!)

Assuming it'll work with your system (my inclination would be to go pressurised) then that's a great place to put it, I've never worried about climbing into lofts. Reckon some guys here are scared of spiders...

Im no expert but the few people I know who have combi's have had problems, I appreciate this could be down to the installer or a cheap boiler, but I would have been up the proverbial creek without a paddle these last few weeks without my water tank! We will be having a new better insulated tank fitted at the same time.

Nothing wrong with them in the right situation, provided you get a good one. As an alternative, if you want a bit of stored water, try something like the Glowworm Ultrastore, they've got a small pressurised hot water cylinder in them and will fit where your existing cylinder is as they're about the same size. Other makes are available, this is just the one I'm most familiar with.

 

[gas4you]

Agree with JohnD. Very good points.
How many among you guys that are servicing boilers would like to clamber into someones loft space with your tool cases?

I do this on a very regular basis, and I am quite large (Well fat is a more appropriate term )

 

[DenG1]

Thanks so much for the input here. I dont have my house measurements available at the moment as Im at work, but will try the calculator over the weekend.

For Tim (I think) who asked about repairing the back boiler, yes this was my first choice had got the new heat exchanger burner and thermostat delivered but its model 675 and the combustion box has corroded to leave a large hole (where Heat Exchanger's been leaking) and this part is obsolete - I have checked this thoroughly myself, after being told by British Gas

Bet my eventual new one wont last 32 years