Which boiler system is best?

housebuyer143

BUFF said:

SAP rating of 76.8 % efficient when new, probably a bit less now.
What sort of controls do you have? Programmer, room 'stat, TRVs?

It's got a room stat, and then the programmer for the hot water and heating, with a time clock, which works as it should. All rads have TRVs as well. 
Boo, 76.8% sounds bad lol.

housebuyer143

Bendy_House said:

housebuyer143 said:

Bendy_House said:

That whole setup doesn't look at all old, and that model - afaIk - was discontinued only 2 years ago.

Almost certainly the leak will be a simple issue to resolve, most likely a leaking fitting seeping down the insulation layer.

I would certainly have that checked over and fully serviced by a good G3, but I think you'd have to be unlucky if it actually needs replacing.

If your heat-only boiler is really kaput, then it should only cost around £1.5-£2k to replace, assuming no complications like awkward flues, etc.

What make and model is it? Again, chances are it can be kept going for a few more years - they are pretty basic devices.

Thank you. It's 19 years old the tank as far as I know and they come with a 25yr guarantee so it seems strange if it was corroded or anything. I have an engineer coming on Tuesday, so I'll ask if he thinks he can diagnose the leak and if not just keep the towels down until my father in law turns up 👍

This is the boiler, again 19 years old. Apart from the occasional fault code it seems okay, I am just concerned it will go down in the winter. I am sure it was an F4 fault it was showing.

It's extremely unlikely that the tank itself is leaking.

And that GlowWorm - although not the more efficient condensing type - has very little serious stuff to go wrong with it. As said before, F4 is an 'ignition' fault, but that could range from very cheap ignition electrodes (£25-ish new), to a gas valve (£30 refurb) or fan (£30 refurb). And in between are PCBs (only ~£35 for a repaired item) and stuff! Ie, these are all available, and very affordable. You just need a half-competent GasSafe to diagnose the actual fault, and be willing to fit a refurbished part.

And refurbished parts should last many years - I've replaced PCBs and fans, and the quality of the refurb was superb. All from very well established companies on eBay.

Thank you. I think the engineers I have had are just too quick to say it needs a new boiler and be done with it. Maybe it's the easiest and most cost generating solution for them.

I'll get some more engineers around and explain I want them to diagnose the fault and fix it, not replace and see if any of them suggest it can be done. 

This has been super helpful as I would have just changed these things and in reality they do not seem to need to be done. 

I tracked down the manual for the tank and it makes mention of needing to fill the air inside like periodically or it will cause an expansion value leak... This is really above my knowledge but it does make me wonder if it could be as simple as that and instructions are given on how exactly to do it. Any competent engineer I hope could at least try it.

Bendy_House

housebuyer143 said:

Thank you. I think the engineers I have had are just too quick to say it needs a new boiler and be done with it. Maybe it's the easiest and most cost generating solution for them.

I'll get some more engineers around and explain I want them to diagnose the fault and fix it, not replace and see if any of them suggest it can be done. 

This has been super helpful as I would have just changed these things and in reality they do not seem to need to be done. 

I tracked down the manual for the tank and it makes mention of needing to fill the air inside like periodically or it will cause an expansion value leak... This is really above my knowledge but it does make me wonder if it could be as simple as that and instructions are given on how exactly to do it. Any competent engineer I hope could at least try it.

That expansion valve 'leak' will not be a damp patch oozing out the side of your tank, but will be a controlled discharge which will be visible via the 'tundish' - that open thingy in the pipework. If you follow the pipe ringed yellow coming out the side, you should find a fitting which is the open end of the pipe pointing down in to a small tapered receptacle. The round red thing will be the 'expansion valve', and is designed to open at a certain pressure, and release excess water safely.

 

If you trace that pipe as it heads off to the floor, and locate the tundish, you can stick yer finger in to it and see if there's any water at the end of that upper pipe end. If there is, then the exp valve is opening, and that will likely be due to excess pressure. The air bubble will need recharging.

Basically, you need a good plumber to give it all a good going-over. Remember that they need to have the further G3 qualification to work on the pressurised tank.

Is FIL going to have a gander at it?

You have a good setup there, and it's been working well for you. It's also been cheap to run as you are clearly careful not to use it excessively. I wouldn't, in your case, be considering a combi boiler, but that's your call. I would be hoping to keep the existing going for a few more years, as that's the MSE way - ie, how to save money.

Yes, condensing boilers can be over 90% efficient, but, to heat that hot cylinder will require an output temp from the boiler which will put it well in to the not-very-condensing temp area, and also, to heat your existing radiators properly, it's likely that your CH output temp will also have to be higher than ideal. You'd struggle to have the boiler outputting at less than 65-70oC, I think, so I suspect it'll only be partially condensing. Stab-in-the-dark figure? 85% efficiency? That's not that much better than what you have.

When the 'change' does happen to alternative heating sources, these tend to work at lower water temperatures, so will either require larger radiators to output enough heat, or else a large jump in insulation value in the house.

housebuyer143

Bendy_House said:

housebuyer143 said:

Thank you. I think the engineers I have had are just too quick to say it needs a new boiler and be done with it. Maybe it's the easiest and most cost generating solution for them.

I'll get some more engineers around and explain I want them to diagnose the fault and fix it, not replace and see if any of them suggest it can be done. 

This has been super helpful as I would have just changed these things and in reality they do not seem to need to be done. 

I tracked down the manual for the tank and it makes mention of needing to fill the air inside like periodically or it will cause an expansion value leak... This is really above my knowledge but it does make me wonder if it could be as simple as that and instructions are given on how exactly to do it. Any competent engineer I hope could at least try it.

That expansion valve 'leak' will not be a damp patch oozing out the side of your tank, but will be a controlled discharge which will be visible via the 'tundish' - that open thingy in the pipework. If you follow the pipe ringed yellow coming out the side, you should find a fitting which is the open end of the pipe pointing down in to a small tapered receptacle. The round red thing will be the 'expansion valve', and is designed to open at a certain pressure, and release excess water safely.

 

If you trace that pipe as it heads off to the floor, and locate the tundish, you can stick yer finger in to it and see if there's any water at the end of that upper pipe end. If there is, then the exp valve is opening, and that will likely be due to excess pressure. The air bubble will need recharging.

Basically, you need a good plumber to give it all a good going-over. Remember that they need to have the further G3 qualification to work on the pressurised tank.

Is FIL going to have a gander at it?

You have a good setup there, and it's been working well for you. It's also been cheap to run as you are clearly careful not to use it excessively. I wouldn't, in your case, be considering a combi boiler, but that's your call. I would be hoping to keep the existing going for a few more years, as that's the MSE way - ie, how to save money.

Yes, condensing boilers can be over 90% efficient, but, to heat that hot cylinder will require an output temp from the boiler which will put it well in to the not-very-condensing temp area, and also, to heat your existing radiators properly, it's likely that your CH output temp will also have to be higher than ideal. You'd struggle to have the boiler outputting at less than 65-70oC, I think, so I suspect it'll only be partially condensing. Stab-in-the-dark figure? 85% efficiency? That's not that much better than what you have.

When the 'change' does happen to alternative heating sources, these tend to work at lower water temperatures, so will either require larger radiators to output enough heat, or else a large jump in insulation value in the house.

Thank you. I did see some water dripping from the tundish and wasn't sure if that was meant to be doing that. 
I will certainly look for a gas engineer specialising in unvented cylinders. How do I know if they have a G3 rating? 

The father in law lives 2 hours away, so he will come, just depends when he finds the time. 

Bendy_House

No, there shouldn't be a drip. And the reason the tundish is there is so you can CHECK whether there is.

The drip from there is 'fine' in itself as it's clearly doing its safety job, so - once sorted - it'll stop. But it does indicate an issue that NEEDS resolving, and most likely this is due to the 'bubble', as the pressure would appear to have increased too high.

The damp-causing leak will be from elsewhere, tho', so that needs tracing and sorting too. Most likely it'll be from around where one of these pipes connect into the tank. If so, the joint will likely need redoing, or perhaps just 'nipped' up.

G3? I guess you ask! You should find they'll state this on their website, tho' as it's a nice extra feature they can provide. Best possible way to find a plumber is to get a personal recommendation from friends, neighbours, work colleagues.

The FIL bit is your call. If he is 'competent', he'll know what to do, and know he's doing it properly. I'm not sure if it's 'legal' for him to do G3 work - it certainly wouldn't be if he was being paid - so don't offer him any tea or biscuits while he is there.

Only kidding. But it's your call. And possibly the law's.

I've done lots of work on boilers including installing a couple. Highly dodgy if I got it wrong, of course, so I made sure I didn't. So, technically 'legal'. And I'm still alive to tell the t

housebuyer143

Bendy_House said:

No, there shouldn't be a drip. And the reason the tundish is there is so you can CHECK whether there is.

The drip from there is 'fine' in itself as it's clearly doing its safety job, so - once sorted - it'll stop. But it does indicate an issue that NEEDS resolving, and most likely this is due to the 'bubble', as the pressure would appear to have increased too high.

The damp-causing leak will be from elsewhere, tho', so that needs tracing and sorting too. Most likely it'll be from around where one of these pipes connect into the tank. If so, the joint will likely need redoing, or perhaps just 'nipped' up.

G3? I guess you ask! You should find they'll state this on their website, tho' as it's a nice extra feature they can provide. Best possible way to find a plumber is to get a personal recommendation from friends, neighbours, work colleagues.

The FIL bit is your call. If he is 'competent', he'll know what to do, and know he's doing it properly. I'm not sure if it's 'legal' for him to do G3 work - it certainly wouldn't be if he was being paid - so don't offer him any tea or biscuits while he is there.

Only kidding. But it's your call. And possibly the law's.

I've done lots of work on boilers including installing a couple. Highly dodgy if I got it wrong, of course, so I made sure I didn't. So, technically 'legal'. And I'm still alive to tell the t

Thank you, this is all so helpful!
The FIL installed the combi in my old house when he was gas safe registered and did a wonderful job. I suppose he has a vested interest in not killing us all, being his only family and all ha ha.

BUFF

Bendy_House said:

Yes, condensing boilers can be over 90% efficient, but, to heat that hot cylinder will require an output temp from the boiler which will put it well in to the not-very-condensing temp area, and also, to heat your existing radiators properly, it's likely that your CH output temp will also have to be higher than ideal. You'd struggle to have the boiler outputting at less than 65-70oC, I think, so I suspect it'll only be partially condensing. Stab-in-the-dark figure? 85% efficiency? That's not that much better than what you have.

When the 'change' does happen to alternative heating sources, these tend to work at lower water temperatures, so will either require larger radiators to output enough heat, or else a large jump in insulation value in the house.

I disagree slightly.
I don't know how long the pipework between the boiler & the tank is nor how well insulated that pipework is but I suspect that a condensing boiler could be run at a temp to provide 60C in the tank & still condense so I would suggest 87-90% for efficiency on DHW.
Nor do I know the size of radiators but many houses typically have oversized (in output terms) rads. The boiler runs longer (but more efficiently)  because of the lower temps so even if not oversized the boiler just runs a bit longer again. Whilst the existing controls should be pretty good a controls upgrade with a new boiler should also gain a few % improvement.

Overall, I wouldn't be surprised to see a 20% (or more if you use the improved controls to also change your heating behaviour) improvement. What we may not have is a record of a full year's gas consumption in order to work out what that saving  would equate to in £s & therefore potential payback time. However, e.g. 20% for the "average" house use of 12,100kWh gas (& we know that this is a large house) at the upcoming 10.4p/kWh for gas would be a £500/year saving.

housebuyer143

Update. 

I called the manufacturer who says the tank is 11 years old. 
They will come tomorrow to look at it and either repair it or give me a free tank if it's broken 🤞🤞 
Watch this space. 

Clive_Woody

Bendy_House said:

Clive_Woody said:

We’ve got an unvented water tank and had solar panels fitted start of the summer. We’ve barely used more than a couple of units of gas since (only used gas when my dear daughter emptied the tank with one of her “epic” showers and someone else wanted a shower urgently). As output decreases through the darker months we will be using some gas to heat the water, but very glad we’ve got a tank to use “spare electricity” as the feed in tariff is rubbish. We also have a battery, and we haven’t been quite off grid over the summer, but our bills have been trivial - 4 bedroom house, me WFH and wife at home all day, kids with far too many electrical gadgets….

As other said, I would get someone in to see if the tank can be sorted and the boiler kept ticking over. Might cost a couple of hundred, but a lot cheaper than a total refit, if not needed.

That's really interesting, Clive - I've been hoping to hear about a real-world setup where surplus PV is used to top up a tank. Which control unit are you using to send the surplus to the immersion?

We have a Solar iBoost fitted. Really impressed to be honest - I actually enjoy reading the gas meter these days :-) 

Bendy_House

Clive_Woody said:

We have a Solar iBoost fitted. Really impressed to be honest - I actually enjoy reading the gas meter these days :-) 

That's just cruel!