Got a combination boiler,it started leaking all over the place last night.
Got an emergency plumber in today at £57 / half hour plus VAT.
He told me it's the heat exchanger ( will confirm this with Ideal Boilers tomorrow) although he didn't pinpoint the leak.
He's quoting £1500 all in for a new boiler.
Our house is a small 3 bedroom end terrace - the current boiler size is 90,000 Btu/h and the one he recommended is exactly the same size, this is despite telling him we are extending next year and would need a bigger boiler.
So.......any recommendations? Should I get a new boiler now (condensor or combi) or should I get a new heat exchanger fitted as we'll be extending next year and will have to get a new boiler anyway?
BTUs are a deprecated unit, but 90,000 of them equates to 26kW which is a fairly powerful boiler for a small house.
Having said that, if it is an older property with solid brick walls with no cavity or no cavity insulation, it may be close to its limit. The only way that you could tell properly is by calculating the heat losses and doing so properly. For an older property, by far the largest losses are through the walls so it is important to check properly and not rely on some plumber looking around and guessing with a ready reckoner. The radiator manufacturers have programs on their web sites to help calculate the heat losses. All you have to do is measure the surfaces (floors, walls, windows) and plug them into the program, room by room, choosing the correct material for each surface. You'll then get a total heat loss for the property. Add about 20% to this for boiler sizing.
When you add an extension, modern building regulations are going to require cavity walls and double glazing and the heat losses in this part are going to be a lot less (could be only a quarter) of the equivalent size of existing house.
I would draw a line under the existing boiler and get a new one. Generally the heat exchanger is one of the most expensive parts.
Are you happy with the hot water performance of the combi? If not, and the water flow is adequate you could go for a larger one with more output to hot water.
Modern condensing boilers (and you can get condensing combi boilers) tend to have control systems which result in the boiler running at a lower than full output (called modulation) to the heating when there is less demand on a warmer day. For the hot water, and when required for the heating, it will run at full power.
So it doesn't matter if you oversize the boiler for heating purposes particularly. You could go for a 30-35kW boiler for example.
Whether the £1500 is a good price depends on what you would be getting. It's worth spending a bit more for a decent condensing product like Vaillant or others with a stainless steel heat exchanger since these have a longer lifetime than most other materials. You would most likely not get one of those fitted for £1500 though,
Certainly it is worth going for a condensing model as you'll shave approx 25% or so off of your energy consumption if the existing boiler is a fairly old type. Do make sure that the system is properly flushed and dosed with corrosion inhibitor as this may have been a contributing factor to the demise of your existing boiler.
Also, if you do have an older property, and it is practical, consider insulating the insides of the outside walls. Something like 50mm Celotex sheet would have an enormous difference with solid walls.
Are you sure that you would need a bigger boiler? Combi's often have spare heating capacity as they have to have the output to heat the DHW anyway. A 3 bed terrace probably only needs around 50,000 BTU
We have a '100,000' Btu/h combi in and extended (extra room and bigger kitchen) 3 bed 1930's semi. The old boiler was IIRC 50-60,000 BTU. The heating output of Combis is adjustable. ISTR that when I installed our combi (as part of an extended CH system) I set the heating output to somewhere in the 60-70,000 range.
So I'd want to check if I really did need a bigger boiler first - do some heat loss calc's on the projected extended house. Myson used to have a free heat loss calculator to download, dunno if they still do.
However, if for whatever reason you would need to change the boiler next year then renewing the heat exchanger doesn't seem worth it, given that it's an expensive job.
Indeed, I've heard of cases where adding a two storey extension has actually resulted in reduced calculated heat losses from the house. This is because an uninsulated solid wall was appended by the heavily insulated 2 storey extension, which had considerably lower heat loss than the original wall, despite have many times the surface area.
The old external uninsulated solid wall then becomes internal with a lot of thermal mass. This, once charged with heat reduces the peaks of heat demand.
Unless the extension has a lower roof pitch than the original (using dormer windows for the upstairs to maintain the same cill height) which means you have a nasty cold radiator where by part of the original gable wall is exposed but connected the rest of it which is now within the house.
PS In all the house makeover, 'get rich quick' etc program, how come I never hear Ms Beeny and others mentioning the magical word 'insulation' to make the property more comfortable?. Lets face it, if you are replastering the walls, why not put up insulated PB and skim that instead ?
Very true. Air leakages account for 42% of heat loss in a modern house. An old Victorian solid walled house with modern sealed double glazed windows and doors is much tighter than the modern equivalent, which, with cavity walls leaks far more. A prime leakage point is the window reveals and where the joists penetrate the inner wall. This should be fully sealed up, but never is.
Ms Beeny know anything about building? Please! She knows about kitchens and paint colours, that's all. A well insulated house is far more attractive to a buyer.
I think that that depends on the buyer. I have not seen many estate agent's particulars on properties emphasising insulation. I've seen plenty extolling the virtues of a Smallbone kitchen. Whether that is right or wrong or not is one thing, but it would appear that they find that their customers find fixtures and fittings important as purchasing criteria.
"Andrew" wrote | PS In all the house makeover, 'get rich quick' etc program, | how come I never hear Ms Beeny and others mentioning the | magical word 'insulation' to make the property more | comfortable?. Lets face it, if you are replastering the | walls, why not put up insulated PB and skim that instead ?
Because it adds to the costs and produces no corresponding increase in sale price. This is property development, ie tart it up cheap and sell quick. Expenditure goes on what the customer sees and will pay for, not on 'good' things that are hidden from view. There is usually not even the requirement of Building Regs to put in insulation, as there is with new build.
The client instructs the estate agent and what points to highlight. Most agents are technically brain dead. There is a famous case in Milton Keynes, when one of the country's first superinsulated houses went up for sale in Energy Park. The stupid agent dropped the price by 2.5K as it never had a heating system. He had to be taken to one side and have it explained to him, even then he couldn't see it. Duh!
If there are two well appointed identical houses in the same road, and one has heating bills of 500-600 a year and one only £50-100, guess which one would attract most attention, sell very quickly and command a higher price.
"IMM" wrote | Ms Beeny know anything about building? Please! She knows | about kitchens and paint colours, that's all. A well | insulated house is far more attractive to a buyer.
Have you read her Property Ladder book?
I was reading part of it in WHSmiths yesterday and she has an 'interesting' viewpoint of the relative merits of combi boilers and instant electric showers.
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