Swapping out old heat only boiler, so many choices

[theboots]

We moved in late December last year, approx. 30 year old 80,000 BTU Potterton with no controls so January was pricy and I fitted a Netatmo wireless room stat. I knew we wanted/needed to switch it out both before it croaks and as it is expensive to run . It is obviously from the age a heat only boiler on a S-plan with 2x linked hot water cylinders in the loft and steel radiators throughout. I am sure there is some sludge in the system too, and I think for sure the living room radiator is undersized especially given my wife feels the cold, albeit there is a gas fire in there for supplemental heating. I need to aim to hit at least 23 in the living room for her.

I was considering a Heat Pump but long story short the final quote after a lot of back and forth was ridiculously expensive at £19k for a moderate sized bungalow. Still I now know from the paid for survey that my heat loss is 12kW.

I am now going around the same route with getting quotes to swap it out for a gas boiler only two in so far but already I am getting a number of options any advice on these would be appreciated. I think I'll switch to a combi, for two of us having maybe 300 litres of 60 degree water permanently in the loft plus the cold water tanks seem an overkill and I'd assume if we went for another system boiler I'd need to at least change the pump and the valves too.

1. 27kW Atag
2 Vaillent 826
3 Worcester 4000
4 Glowworm 30kW but they'll fit whatever I want and recommend swapping out the current TRV and lockshields also they are the only one to suggest an upgrade for the living room radiator to a triple panel type 33 (currently a 1600x600 type 21).

The first three are all the same company and the only one I yet have prices for £5K +/- a bit depending on boiler choice. Both have pointed out I need to upgrade the 15mm gas pipe as we have both the boiler and the gas range fed from the same pipe right now although it leaves the meter on 22mm it reduces somewhere. I'd plan to change the TRV heads for wireless units at some point as I go I don;t know if to try and source Netatmo ones to match the room stat or maybe Tado given I am starting from almost the beginning again.

 

[flameport]

A combi boiler will tie you to gas forever, as all heat pumps and other electric heating options require a hot water cylinder.
Combi also means zero options for using solar power for hot water.

If two cylinders are not required, delete one of them.

The existing boiler is 2x larger than it needs to be.

 

[Harry Bloomfield]

for two of us having maybe 300 litres of 60

Two of you, with just one bathroom, the 300L is far more than you need. Even if you each take a bath, sequentially, 30 minutes or so, would see the hot water mostly replenished, if you had just a 120L hot water cylinder.

 

[Justin Passing]

Mate has a Vaillant Storage Combi. 940 I think. Make sure you get the 10 year warranty.

Impressive hot water performance. In practice, no need for a cylinder it heats up so quickly between baths. Standard boiler size but deeper.
Needs a good mains water supply to keep up.
Others will disagree.....

Get decent LS rad valves. Most are crap. Look for a nut on the shaft to tighten the seal, like a stopcock has. Most are just pressed together. You turn one in a couple of years time, 50% chance it'll leak. Peglers are expensive but good. "British Standard " ones used to be what to look , cheap enough, for but I dion't see any now.
A decent drain cock low down somewhere saves grief too. A Washing machine hose will fit 3/4 bsp, and they won't leak like the 37p ones (I'm old). This type.. You can take the handle off. One on each side if you can, great for future mains flushes.

 

[Harry Bloomfield]

Mate has a Vaillant Storage Combi. 440 I think. Make sure you get the 10 year warranty.

Impressive hot water performance. In practice, no need for a cylinder it heats up so quickly between baths. Standard boiler size but deeper.
Needs a good mains water supply to keep up.
Others will disagree.....

The storage combi, has the same disadvantage as a normal combi, in that the Kw input needs to be great enough, to instantly heat the cold water to usable temperature, but the slight advantage that a small quantity of hot water will be instantly available for washing up/handwashing.

80,000 BTU, is around 24kw, which if the heat loss assessment is correct, is double the Kw actually needed. Most economic gas use, is with a correctly sized boiler installed, but modern boilers, both combi and heat only, are able to modulate their output down, which helps.

Aside from your heat only boiler, being able to have a full cylinder of hot water, ready to use - Depending on how you use it, one could potentially be more economical on gas use. A heat only boiler is cheaper, and much less complex internally, less to go wrong inside, needing a gas engineer to fix it, plus cheaper to install, assuming your present loft tank and cylinder are in good condition.

 

[Justin Passing]

The storage combi, has the same disadvantage as a normal combi, in that the Kw input needs to be great enough, to instantly heat the cold water to usable temperature, but the slight advantage that a small quantity of hot water will be instantly available for washing up/handwashing.

80,000 BTU, is around 24kw, which if the heat loss assessment is correct, is double the Kw actually needed. Most economic gas use, is with a correctly sized boiler installed, but modern boilers, both combi and heat only, are able to modulate their output down, which helps.

Aside from your heat only boiler, being able to have a full cylinder of hot water, ready to use - Depending on how you use it, one could potentially be more economical on gas use. A heat only boiler is cheaper, and much less complex internally, less to go wrong inside, needing a gas engineer to fix it, plus cheaper to install, assuming your present loft tank and cylinder are in good condition.

Actually not, Harry. Though it's a relatively small amount of storage, it's hot already so it does not instantly have to be heated, it's there. The effect is surprisingly useful. Then, 40kW is 4 times as much as a typical electric shower. That fires up immediately so the stored water is blended in over the fisrt few minutes. Perhaps you haven't experienced one.
On the heating side also, the boiler is happy to operate from 5kW or so, automatically, so it's not "more than is needed."

Gasbag should be able to confirm, because he's up to date and I'm not, but it looks like the silly little tw@ is trying to set up a conflict because that's what he is. He's already been posting twaddle about gas pipe requirements so maybe he's mentally going off.
I expect the mods will be on him, as they apparently were when I was semi-conscious and off line in hospital for a few weeks.

 

[Harry Bloomfield]

Though it's a relatively small amount of storage,

How small, I couldn't find a spec for it?

He's already been posting twaddle about gas pipe requirements so maybe he's mentally going off.

Well, the chances are, a switch from a heat only, to a combi might well need a larger gas supply pipe run to it.
Of course, but that wasn't the issue.

 

[theboots]

A combi boiler will tie you to gas forever, as all heat pumps and other electric heating options require a hot water cylinder.

At £26K before the grant the heat pump option is sadly a non starter, it is going to be IRO of £15K more than a boiler install.

Combi also means zero options for using solar power for hot water.

If two cylinders are not required, delete one of them.

Even with the current boiler and keeping way too much stored hot water the bill for that is around 70p a day. It is 90% of the time two of us showering.

The existing boiler is 2x larger than it needs to be.

I realise that, I think that's a hangover from the old days where boilers were always upsized.

Well, the chances are, a switch from a heat only, to a combi might well need a larger gas supply pipe run to it.

I think that's on the cards, the ovens here are gas too. Even if we opt for a heat only boiler keeping one or both tanks, those tanks, the 2-port valves and the pump are all of a similar vintage to the boiler. I think fiscally it is going to have to be a boiler the choices are which manufacturer and I'll see how long the list is once the final two quotes are in and combi which means all new pump and valves or a system boiler and then do I need to consider swapping out also the ancillary parts of the system

 

[dilalio]

Heat only cost more than combis.
You won't have the backup of an immersion if going for a combi and your mains flow rate needs to be decent.

 

[gas112]

Your ad hom comment has been deleted,
You did earlier give incorrect gas advice.
Some mods are GSR as I am currently.
Please be more careful and not abusive.

Thread ban.

 

[Harry Bloomfield]

Heat only cost more than combis.

??

 

[dilalio]

??

They are.
Mass produced nowadays.

 

[Harry Bloomfield]

Even if we opt for a heat only boiler keeping one or both tanks, those tanks, the 2-port valves and the pump are all of a similar vintage to the boiler.

A quick, cheap job to replace with new.

 

[Harry Bloomfield]

They are.
Mass produced nowadays.

£1,170 Vaillant 418 heat only - https://www.mrcentralheating.co.uk/boilers/boilers-by-brand/vaillant-boilers/heat-only-boilers

Probably the lowest Kw/ cheapest combi the OP might need....
£1,291 Vaillant ecoTEC Pro 30 Combi Boiler - https://www.mrcentralheating.co.uk/vaillant-ecotec-pro-30-condensing-combi-boiler

 

[flameport]

t £26K before the grant the heat pump option is sadly a non starter, it is going to be IRO of £15K more than a boiler install.

True today for whatever and whoever quoted that.
Will be entirely different in a year or five when you may regret disposing of the hot water cylinders.