corgigasman   10 #769 Posted June 13, 2014 Does anybody know how to size a combi boiler? I have found this online sizing tool - has anybody used it?  http://calculators.baxiknowhow.co.uk/boiler-sizing/  For my smallish bungalow it says I need a 11.5KW boiler.  The smallest ones available seem to be 25KW ish  Any comments or advice will be welcome  Smallest standard combi's are 24kw, this will be more than adequate for most properties with less than 10 radiators for the heating side, you would only require a larger boiler for hot water output (depending on flow-rate of your mains).....typically 24kw give 'adequate' output at about 9.5 litres per minute, where as larger combi's have greater outputs (40kw = 16 l/min). There is generally no need for bigger outputs unless you expect multiple H/W demand (ie multiple bathrooms). You will always get very hot water just by running the tap slower so 24kw may well be adequate. I always like to demonstrate a tap running and ask if the customer finds a particular flow-rate adequate IN THEIR OPINION....ultimately it is the customers' choice, gas engineers are happy to explain and advise, regards, Steve Share this post Link to post Share on other sites Share this content via...
5iron2   10 #770 Posted June 13, 2014 Smallest standard combi's are 24kw, this will be more than adequate for most properties with less than 10 radiators for the heating side, you would only require a larger boiler for hot water output (depending on flow-rate of your mains).....typically 24kw give 'adequate' output at about 9.5 litres per minute, where as larger combi's have greater outputs (40kw = 16 l/min). There is generally no need for bigger outputs unless you expect multiple H/W demand (ie multiple bathrooms). You will always get very hot water just by running the tap slower so 24kw may well be adequate. I always like to demonstrate a tap running and ask if the customer finds a particular flow-rate adequate IN THEIR OPINION....ultimately it is the customers' choice, gas engineers are happy to explain and advise, regards, Steve  Hi - Thank you for your advice.  Yes my property has only 8 radiators of which 2 are quite small. So it seems that the 24kw would be more than adequate for the space heating side. So if I understand you correctly it really depends on the hot water demand. We have only 1 bathroom, plus a kitchen and wc room(with hand basin), so it would seem the 24kw would be adequate.  I suppose the question is - what is the difference in price between the two units 24kw v 30 kw? Share this post Link to post Share on other sites Share this content via...
corgigasman   10 #771 Posted June 13, 2014 Usually about £100 between a 24 and 30 kw, dependent on make and model....some a bit more differential, some a little less Share this post Link to post Share on other sites Share this content via...
Micky ET Â Â 10 #772 Posted June 14, 2014 It is the f flow rate on the hot water if you have or plan to use a bath go for a 28Kw if not 24 Kw will be okay Share this post Link to post Share on other sites Share this content via...
5iron2 Â Â 10 #773 Posted June 25, 2014 If you need a new boiler installed, look no further than Met Gas Services. They have just installed a new combi boiler for me and the service, promptness and quality of work was second to none!!! Â Even fitted a washing m/c supply free of charge !!! Â http://www.sheffieldforum.co.uk/member.php?u=58408 Share this post Link to post Share on other sites Share this content via...
113100 Â Â 10 #774 Posted June 27, 2014 Hi! Had new Greenstar 28i Junior Combi boiler just fitted. The pump will come on and run for a few minutes, then intermittently there will be water leaking from bottom of boiler (only last a few seconds) I have noticed there is plastic pipe going into boiler but it is not connected to anything. Is there any connection (or not) between this and the leak? Share this post Link to post Share on other sites Share this content via...
JBradleybz   10 #775 Posted June 28, 2014 Hi! Had new Greenstar 28i Junior Combi boiler just fitted. The pump will come on and run for a few minutes, then intermittently there will be water leaking from bottom of boiler (only last a few seconds) I have noticed there is plastic pipe going into boiler but it is not connected to anything. Is there any connection (or not) between this and the leak?  Happy to take a look for you but if its a new install get the company back who fitted it for you cheers Jon at JB Heating. Share this post Link to post Share on other sites Share this content via...
watchcoll   10 #776 Posted June 30, 2014 Hi all, I'm thinking of finally replacing the ancient heating system that came with my house when i bought it. The current system is a very old unreliable boiler in the kitchen, water tanks upstairs. Rather than trying to repair it i want to replace it.  Is it possible for anyone to give me a rough idea of how much it would cost? I thought i'd ask here before getting busy professionals out to quote & wasting their time if i can't afford it yet. Details are: Remove old water tanks etc from upstairs. Run new 22mm(?) pipes from meter in cellar up to first floor, under floorboards & then back down to kitchen underneath. Current pipes are 15mm. Replace old boiler with new combi. Flush all heating system etc. Put in room thermostat as there currently isn't one.  House is a small two bed terrace, single occupant. 5 radiators, one very big one in the lounge. Bathroom has a bath that gets used a couple of times a week & an electric shower. I'd really like to get rid of the current system as it's so expensive keeping a full tank of water hot in summer just to wash my hands & the dishes!  Any ideas anyone? Or can anyone recommend types of boilers to look at? Share this post Link to post Share on other sites Share this content via...
d71146 Â Â 10 #777 Posted June 30, 2014 Hi all, I'm thinking of finally replacing the ancient heating system that came with my house when i bought it. The current system is a very old unreliable boiler in the kitchen, water tanks upstairs. Rather than trying to repair it i want to replace it. Â Is it possible for anyone to give me a rough idea of how much it would cost? I thought i'd ask here before getting busy professionals out to quote & wasting their time if i can't afford it yet. Details are: Remove old water tanks etc from upstairs. Run new 22mm(?) pipes from meter in cellar up to first floor, under floorboards & then back down to kitchen underneath. Current pipes are 15mm. Replace old boiler with new combi. Flush all heating system etc. Put in room thermostat as there currently isn't one. Â House is a small two bed terrace, single occupant. 5 radiators, one very big one in the lounge. Bathroom has a bath that gets used a couple of times a week & an electric shower. I'd really like to get rid of the current system as it's so expensive keeping a full tank of water hot in summer just to wash my hands & the dishes! Â Any ideas anyone? Or can anyone recommend types of boilers to look at? I recommend Steve (CorgiGasMan on the Forum he did a great job installing a new system in 2012 he will give you a written quotation on a job unlike some others. Share this post Link to post Share on other sites Share this content via...
JBradleybz   10 #778 Posted June 30, 2014 Hi all, I'm thinking of finally replacing the ancient heating system that came with my house when i bought it. The current system is a very old unreliable boiler in the kitchen, water tanks upstairs. Rather than trying to repair it i want to replace it.  Is it possible for anyone to give me a rough idea of how much it would cost? I thought i'd ask here before getting busy professionals out to quote & wasting their time if i can't afford it yet. Details are: Remove old water tanks etc from upstairs. Run new 22mm(?) pipes from meter in cellar up to first floor, under floorboards & then back down to kitchen underneath. Current pipes are 15mm. Replace old boiler with new combi. Flush all heating system etc. Put in room thermostat as there currently isn't one.  House is a small two bed terrace, single occupant. 5 radiators, one very big one in the lounge. Bathroom has a bath that gets used a couple of times a week & an electric shower. I'd really like to get rid of the current system as it's so expensive keeping a full tank of water hot in summer just to wash my hands & the dishes!  Any ideas anyone? Or can anyone recommend types of boilers to look at?  Happy to quote for your new boiler installation cheers Jon at JB Heating. Share this post Link to post Share on other sites Share this content via...
EFCMatt   10 #779 Posted July 2, 2014 @Watchcoll - Speak to Mike at METGAS Services 07592 418536 . They have just relocated and replaced my boiler and upgraded parts of my central heating system. Did a great job and Mike gave really good advice.  I would be wary of anyone willing to give a price before coming to survey the property/job Share this post Link to post Share on other sites Share this content via...
watchcoll   10 #780 Posted July 2, 2014 @Watchcoll - Speak to Mike at METGAS Services 07592 418536 . They have just relocated and replaced my boiler and upgraded parts of my central heating system. Did a great job and Mike gave really good advice.  I would be wary of anyone willing to give a price before coming to survey the property/job  Thanks for the recommendation, i've had the same 3 names mentioned by lots of different people so i'll be calling up for quotes soon. Would really like to get it all done before the winter! Share this post Link to post Share on other sites Share this content via...