help with boiler efficiency?

[x51990]

hi, to cut a long story a bit shorter, I am basically looking at buying a new house, it has an old glow worm boiler in the kitchen with a tank upstairs. its apparently 20ish years old. this boiler hasn't been serviced for several years so I asked my friend who is a gasman to have a quick look to just see if the radiators heat up and if I will be getting some hot water from it.. anyway I can get hot water but most of the rads seem to only get hot either top or bottom not all the way through. he didnt want to touch anything as its not officially my house yet but he said there could be some air in the rads which you could just bleed out but also said due to the age of the system they are probably full of crap and would probably benefit from a powerflush or just a new system. whilst trying to agree a price on the house I pointed out about the age of the system (the surveyor had also already done this) and so the current home owner said they would not lower the price but would get the boiler officially serviced with all the relevant paper work. I have just had a call today saying the boiler has been serviced and is running at 94 percent efficiency which I definitely do not think is possible due to the age and it not being condensing? I basically want to know are they lieing to me or could this be possible? also how would they test the efficiency on a boiler this old? from the little knowledge I have I thought you could only do an efficiency reading on a condensing boiler with a flue gas analyser? any info would be really appreciated. thanks very much

 

[Ray Stafford]

They aren't necessarily lying, but they aren't necessarily telling the truth, the whole truth and nothing but the truth.

 

[SimonG]

In January this year you were a last year apprentice, so you should know the answer or at least know someone who knows the answer.

 

[Ray Stafford]

In January this year you were a last year apprentice, so you should know the answer or at least know someone who knows the answer.

Good spot!

 

[x51990]

Not really that great of a spot! Didn't finish my apprenticeship and not claiming to be a gasman, just looking for an answer to my question if that's not to much to ask! Thanks

 

[SimonG]

Maybe you didn't finish but you had been using a fga (according to your previous posts) so should know how they can be used to give whatever info you need.

Bottom line wether they are being economical with the truth or not is, you have at least a boiler that's going to need changing sooner rather than later and a system that needs at least a good clean.

It's then down to you to negotiate with the vendor or walk away.

Personally if they have a bit of paper that says that a boiler of that age is running at 94% I'd be telling them to file it where the sun doesn't shine.

 

[x51990]

Thanks alot for the response. I basically got put on a fast track gas course with very little practical experience found it very difficult and gave up in the end to be honest. Didn't feel I could learn everything in such a short amount of time. I did a bit of fga just on condensing boilers. Out of interest is it possible to use the fga probe on an old boiler like this to get an efficiency reading? If not then how would this gasman of possibly calculated his 94%? Thanks

 

[Dotty]

Out of interest is it possible to use the fga probe on an old boiler like this to get an efficiency reading?

Yes.

As stated before you'll probably find a low flue temp enabling the efficiency rating to be massaged.

If you look in MI's all manufacturers state the boiler must be run for 10-15 minutes on average to come up to temp before any FGA tests be carried out.