I am going to get extremely technical now! The pipework going into the boiler at the bottom (I guess from the main supply) is quite narrow. The 2 pipes coming out of the top of my boiler are quite chunky. Which pipes would require replacing for a bigger boiler - all of them?
What Size/Model Boiler?
- Thread starter simmodave
- Start date
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More technical information! The Gas Boiler is probably sited no more than 12' from the gas meter outside the house. The pipework from the meter appears to be about the same size as the 2 pipes coming out of the top of the boiler. The narrowist pipe is the one the runs from the main gas pipe to the bottom of the boiler itself.
Without being there to see it for myself, it certainly sounds as though this would be adequate for the 18Kw and possibly a 24Kw boiler.
If other appliances come off it or there are lots of elbows in it, then it may not.
I can only suggest asking your proposed installer whether he has taken into account the gas pipe sizing and calculated it himself.
If other appliances come off it or there are lots of elbows in it, then it may not.
I can only suggest asking your proposed installer whether he has taken into account the gas pipe sizing and calculated it himself.
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Thanks gas4you. One final question and I will leave you in peace. If the pipework is adequate for the Solo 18 and it is indeed fitted. What is the worst that could happen if (because of the amount of radiators I have) I really should have had the Solo 24 fitted. The radiators will still get hot won't they, and the water?
The radiators would still get hot, but if it were massivly undersized it would take forever to do it.
The simplest way for you to check is to measure your rads length x height, see if they are doubles or singles, whether they have fins on the back, then look up these sizes, or as near as you can in a rad catalogue, add all the outputs together and this will tell you what heat they are capable of emitting at 50C water temp (the current standard).
Add another 3Kw for the hw cylinder and size the boiler to this total.
Chances are if you have had double glazing, cavity insulation, extra loft insulation etc, done since this system was fitted, they will be oversized now anyway.
As a side thought, I only ever fit Band A boilers. I believe the Solo is a Band B boiler.
The simplest way for you to check is to measure your rads length x height, see if they are doubles or singles, whether they have fins on the back, then look up these sizes, or as near as you can in a rad catalogue, add all the outputs together and this will tell you what heat they are capable of emitting at 50C water temp (the current standard).
Add another 3Kw for the hw cylinder and size the boiler to this total.
Chances are if you have had double glazing, cavity insulation, extra loft insulation etc, done since this system was fitted, they will be oversized now anyway.
As a side thought, I only ever fit Band A boilers. I believe the Solo is a Band B boiler.
The Baxi Solo range are all A Rated according to google searches I have carried out. 8 of my radiators are doubles, all the others (singles) have fins coming out of the back. 4 of the double radiators are in the bedrooms and we do not like the bedrooms too hot anyway. 1 of the double radiators and 4 of the single radiators are quite small (2 x bathrooms and downstairs toilet etc).
If you don't want to do complicated calculations go to Sedbuk website and use the Recommended Boiler Size calculator. This asks a few basic questions about size and construction of house and gives a ball-park boiler size. You should not go far wrong with their recommendation.
I think you will find that 50C is the difference in temperature between water and the air. So at an air temp of 20C the mean water temperature will be 70C; i.e flow 75C, return 65C.
I've always took this to mean the boiler flow temperature and this figure was brought in to align us with european standards and the fitting of condensing boilers.
The rad guides all state
'All radiator outputs are calculated @50C inline with the european BSEN 442 testing standard
Have I been wrong all this time?
The rad guides all state
'All radiator outputs are calculated @50C inline with the european BSEN 442 testing standard
Have I been wrong all this time?
Unfortunately, Yes
Which rad catalogue did you get your info from?
This might help: http://www.plumbingpages.com/featurepages/BSEN442.cfm
The Stelrad Elite catalogue says: Outputs at Operating Temperature 75/65/20ºC and later on has a temperature table headed: Factors for differences between mean water temperature and room temperature ... other than 50°C (90°F)
You are correct in thinking that the change was to bring UK in line with Europe, but I don't think it had anything to do with condensing boilers. A return temp of 65C is above the dew point at which condensing will occur which is about 60C.
Edit
There is a very useful calculator at Engineering Tool Box which will work out the actual heat output for a radiator for different flow, return and room temps. This site has loads of useful goodies.
Well today is certainly a day for me to learn things new
Thanks for pointing that out, I knew about the outputs differing for rad temp and air temp, but never put 2 & 2 together to arrive at this logical conclusion
Thanks for pointing it out and correcting me, but as a heating engineer (oh no I musn't call myself that any more unless I want to work for ASDA ) theory things are not my forte
Thanks for pointing that out, I knew about the outputs differing for rad temp and air temp, but never put 2 & 2 together to arrive at this logical conclusion
Thanks for pointing it out and correcting me, but as a heating engineer (oh no I musn't call myself that any more unless I want to work for ASDA
) theory things are not my forte No need to apologise, an engineer has been defined as the person who turns theory into reality.
ChrisR/Gas4you. You were both correct in saying that the pipes are probably too small even for the boiler I have now - they are! My radiators were measured this morning and ideally I require a Baxi 24 HE to run my system. However, without replacing the pipes (an expensive option) I can only have a Baxi 18 HE. For some strange reason all the radiators in my bedrooms are double radiators - these are wasted KW's as the bedrooms are always far too hot. I have opted for the 18 HE and will have thermostats fitted to the bedroom radiators to reduce the heat upstairs and hopefully, direct the heat downstairs. This may not be the right decision but it is the only option that I can afford at this moment in time. I would like to take this opportunity to wish you all a Very Merry Christmas and a Happy New Year - I, myself, will be working 12 hour shifts on Christmas Day, Boxing Day and New Years Day (luck of the draw!).
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