Am I being spun a line re: efficiency of Camray 5 oil boiler?

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Hi all,

Newb here. I've been reading some of your threads and it seems there are some very smart folks here who may be able to help with a head-baffling question.

We're in a rental home and we have a 20yo oil boiler, the Camray 5 95/130A. It's had the burner replaced with a Riello RD3 that the manufacturer told me today was manufactured in 2003.

The question is, how can my oil boiler be running at 89.5% efficiency gross when sources such as this say it's lower?

https://www.homeheatingguide.co.uk/efficiency-tables?model=008482

I asked the plumber in person how that's possible, I think he was a bit shocked that I'd looked it up, and he said 'it's had some replacement parts.'

Is it possible that any parts could make it more efficient than the URL above? My first thought was the burner, but now I know it's 18 years old, it doesn't seem likely.

I found a thread from 2013 where someone said he'd regularly seen this boiler run at 83-85%, but it's 2021 now!

We've been told all sorts of unlikely things by this plumber such as that it's normal for a radiator to be hot at the top and cold at the bottom, so I'm highly skeptical about this oil efficiency stat on our certificate.

It's in a brick outbuilding that's attached to the house with no insulation (house also not insulated).

Tyvmia.

ps: if you are knowledgeable enough about boilers to tell me if this specific model is too small/old for our house, please let me know and I'll give a description
 
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Impossible to say if boiler right output for properly needs proper heat loss calculations to tell
I certainly doubt its running at nearly 90% efficiency at its age.
Also at its age chances are boiler is in last part of its life.
I would be pushing for better insulation as a first move.
 
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1. It probably isn't 89.5% efficient. Given its age, I'd be surprised if it was 80% efficient.
2. You need to be careful with efficiency figures. 89.5% of what? If it means that 89.5% of the potential heat energy of each litre of fuel is conducted into the system's water, then as 1. above.
3. What certificate are you referring to? if its an EPC, the "surveyor" will probably just have put down some standardised figure for the boiler which will have no adjustment for age.
4. If you are concerned that the system will cost you a lot to run, then:
4a. The most effective single measure is loft insulation.
4b. The second is cavity wall insulation, but this is no good if you have solid brick walls.
4c. Double or triple glazing is probably the next best thing, but the cost benefit ratio isn't particularly good.
4d. A more modern condensing boiler will perhaps be 90% efficient, but with the government hoping to phase them out in favour of heat pumps, replacement may not be sensible.
5. A rental property must currently have an EPC rating of E or better. I don't know whether this applies to renewals or new tenancies only. There are plans to make this a C rating from 2025 for new tenancies.
6. No one can tell whether the Boulter is suited to you property without size and construction details.
 
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He's telling you the combustion efficiency, not the boiler efficiency. Combustion efficiency is shown on his flue gas analyser, and is a calculation of how much of the fuel is being completely burned. With enough fiddling around you can get it very very close to 100%, but that doesn't mean the boiler is 100% efficient, just that the flame is very clean. It could be throwing 50% of its heat in to the atmosphere and still achieve over 90% combustion efficiency. Boiler efficiency is how much generated heat is transferred into system heat, and that is the figure the HHG produces.

As to your final point, if your boiler is heating your home adequately then it is not too small. If it is not leaking all over your floor, it is not too old. The cost of replacing an oil boiler is never ever recouped in savings through increased fuel efficiency in a normal domestic property.
 
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Standard efficiency oil boilers from the last 20 years often have high COMBUSTION efficiency towards the 90%. How that efficiency is utilised is of more importance to the bill payer. More attention needs to be given to the points raised by the other posters above. As Muggles says, if it ain't broke, don't fix it.
 
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Impossible to say if boiler right output for properly needs proper heat loss calculations to tell
I certainly doubt its running at nearly 90% efficiency at its age.
Also at its age chances are boiler is in last part of its life.
I would be pushing for better insulation as a first move.
Do you mean insulation in the home, or the room the boiler is in? They're not going to insulate the house, it's 270 years old, the man who owns it owns another 349, and he's just not going to spend the money.

If insulation in the small outbuilding the boiler is in would make a difference, however, I might be able to convince them to do that.
 
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1. It probably isn't 89.5% efficient. Given its age, I'd be surprised if it was 80% efficient.
2. You need to be careful with efficiency figures. 89.5% of what? If it means that 89.5% of the potential heat energy of each litre of fuel is conducted into the system's water, then as 1. above.
3. What certificate are you referring to? if its an EPC, the "surveyor" will probably just have put down some standardised figure for the boiler which will have no adjustment for age.
4. If you are concerned that the system will cost you a lot to run, then:
4a. The most effective single measure is loft insulation.
4b. The second is cavity wall insulation, but this is no good if you have solid brick walls.
4c. Double or triple glazing is probably the next best thing, but the cost benefit ratio isn't particularly good.
4d. A more modern condensing boiler will perhaps be 90% efficient, but with the government hoping to phase them out in favour of heat pumps, replacement may not be sensible.
5. A rental property must currently have an EPC rating of E or better. I don't know whether this applies to renewals or new tenancies only. There are plans to make this a C rating from 2025 for new tenancies.
6. No one can tell whether the Boulter is suited to you property without size and construction details.

2. I don't know. It just says efficiency gross 89.5% and efficiency nett 95.1%. It also says the flue gas temp is 97.7 degrees C.
3. This is a landlord oil installation check, a CD/12 form, a bit like the annual gas safety inspection certificate, I guess.
4a. They have agreed to more fully insulate the loft during a visit today. At present, only about a third of it is done (it's quite thick, but it's in a state, and very haphazardly fitted with long spaces not covered). They simply haven't bothered with the x2 extensions because there are x2 2ft high brick walls in between the main rectangular part of the loft and these two extensions off the sides of it. b. They are indeed solid brick walls: 1ft thick limestone. In any case, they won't spend money on that sort of thing. c. Not only won't they pay for that kind of glazing but the man who owns these homes likes them looking old; he would never agree to install double glazing. We have a ridiculous number of stipulations of things we can or cannot have surrounding the house because he likes it 'just so.' It's like the American TV shows you see where the local associations insist you keep your lawn at no more than 1 inch and come out with tape measures. He really is that bad, apparently.
5. The EPC rating is 2 points off being illegal, an F. It's only just an E. Part of my concern in posting this thread is that things have been fudged to make them look better than they actually are, hence asking about the boiler efficiency. I know the surveyor would have worked off the SAP system for our model, but I find it hard to believe the boiler can be as efficient as it claims on the certificate, given its age. That puts in in a B category according to the certificate. It just seems unlikely.
6. It's a 270 year old house with 1ft thick limestone walls, no wall insulation. The floors are not insulated. It's a T shape house, almost all of the rooms are exposed on 3 sides. It is 1460 square foot, completely detached, is open to fields at front and back, and has woods on either side (which means light levels are bad and those sides barely get sunlight). There are 15 windows of varying sizes and the house has 14 radiators of varying sizes throughout. The roof tiles, whilst seemingly in excellent condition, seem to be directly affixed to the rafters.

Thanks for all the time you took writing out these questions to help me, I appreciate the time an internet stranger has spent!
 
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He's telling you the combustion efficiency, not the boiler efficiency. Combustion efficiency is shown on his flue gas analyser, and is a calculation of how much of the fuel is being completely burned. With enough fiddling around you can get it very very close to 100%, but that doesn't mean the boiler is 100% efficient, just that the flame is very clean. It could be throwing 50% of its heat in to the atmosphere and still achieve over 90% combustion efficiency. Boiler efficiency is how much generated heat is transferred into system heat, and that is the figure the HHG produces.

As to your final point, if your boiler is heating your home adequately then it is not too small. If it is not leaking all over your floor, it is not too old. The cost of replacing an oil boiler is never ever recouped in savings through increased fuel efficiency in a normal domestic property.

So these certificates can just be fudged to get them to say whatever you want them to say, and this efficiency percentage is just smoke and mirrors? That seems like a pretty awful way to try to get people to be more environmentally friendly.

There are 3 figures. Efficiency nett: 95.1% (I did read up on this a bit, I know a lot of that is lost through condensation), efficiency gross: 89.5%, and flue gas temp: 97.7 degrees C.

It's not heating the home adequately, but we've had them round today to do a chemical flush of the rads, so we'll see how the temp improves over the next few weeks (they have left it in the system for a few weeks).

Can you tell me what 'the figure the HHG produces' means, please?

Many thanks for your help.
 
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Standard efficiency oil boilers from the last 20 years often have high COMBUSTION efficiency towards the 90%. How that efficiency is utilised is of more importance to the bill payer. More attention needs to be given to the points raised by the other posters above. As Muggles says, if it ain't broke, don't fix it.
Yes, and that's the point. We got through 150 litres of oil in our first month here just for hot water. We have been unable to get the rads to work on a 19-20 degree setting, so have to have them all turned up on full, and been spending eye-bleeding (not even eye-watering) amounts of money on oil. I'm talking half our quite substantial rent. One week, we got through 300 litres. Anyway, you'll see from my reply to another post the description of the building, and, in the meantime, the plumbers came by to do a chemical flush today after I put my foot down again, again, again, and eventually quoted temperature laws, council's health and safety departments, and breaking lease terms and instructing lawyers.

Sigh. Sorry, I think I needed to get that out!

Thanks for your reply.
 
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Smoke and air, at least. It may be that your boiler chap genuinely doesn't know the difference between combustion efficiency and boiler efficiency. Combustion efficiency (how completely the fuel is burned) can be varied by adjusting the air and fuel pressure settings. Boiler efficiency (how much heat is transferred into the system vs lost to atmosphere) is a broadly fixed value as a result of boiler design. I say broadly fixed as the ultimate efficiency is also affected by heating system design.

300 litres in a week is an awful lot of oil. Have you had the oil pipe pressure tested to check it's not leaking, and a thorough inspection of the tank?
 
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Smoke and air, at least. It may be that your boiler chap genuinely doesn't know the difference between combustion efficiency and boiler efficiency. Combustion efficiency (how completely the fuel is burned) can be varied by adjusting the air and fuel pressure settings. Boiler efficiency (how much heat is transferred into the system vs lost to atmosphere) is a broadly fixed value as a result of boiler design. I say broadly fixed as the ultimate efficiency is also affected by heating system design.

300 litres in a week is an awful lot of oil. Have you had the oil pipe pressure tested to check it's not leaking, and a thorough inspection of the tank?

That's a bit worrying given that it's their business (a small plumbing firm).

I haven't specifically asked for any of that to be checked. The house spent 10 months being refurbed and you would assume this would all be checked during that process, and during the process of them issuing the oil safety/inspection certificate.

I checked back with the other half and we used 150 litres of oil in our first month here, when we didn't even have the heating on, that was just for hot water, so just even that seems excessive to me. I am wondering if the boiler is running in the background all the time, using up oil, regardless of what it's set to be doing.

However, it's a very, old house, description that I pasted in another reply above:

It's a 270 year old house with 1ft thick limestone walls, no wall insulation. The floors are not insulated. It's a T shape house, almost all of the rooms are exposed on 3 sides. It is 1460 square foot, completely detached, is open to fields at front and back, and has woods on either side (which means light levels are bad and those sides barely get sunlight). There are 15 windows of varying sizes and the house has 14 radiators of varying sizes throughout. The roof tiles, whilst seemingly in excellent condition, seem to be directly affixed to the rafters.
 
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Again, 150 litres doing hot water alone seems to be very excessive. I would be prioritising a pressure test of the oil pipe and thorough tank inspection ASAP.
 
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Again, 150 litres doing hot water alone seems to be very excessive. I would be prioritising a pressure test of the oil pipe and thorough tank inspection ASAP.
As far as I'm aware, they've never had the tank maintained. Foreman thinks it's not necessary because it's double bundled. But it's 18 years old - I checked with the manufacturer yesterday. I don't smell oil when around the tank, I smell a lot of oil when I'm in the room where the boiler is, it hits you in the face as soon as you open the door. You'd think the plumbers would say if that's not normal, wouldn't you? But I think they have an annual contract for a LOT of houses for not a lot of money, so, if keeping quiet means less work... eye roll.

Thanks for the info re: tests. We might pay out of our own pocket to get someone completely unconnected to this whole area in to do an inspection (because the landlord is very special, some people won't even quote for work here: 'he likes his own people.').
 
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