stevie_b Posted April 19, 2012 Share Posted April 19, 2012 The elderly conventional boiler in our house has packed up, and by coincidence the hot water cylinder in the airing cupboard has got a weep on it (which probably isn't economically fixable). I'm undecided whether to go for a combination boiler or stick with a conventional one. I like the idea of doing away with the HWC and the header/storage tanks in the loft, and the pump for the shower. I don't like the idea of the 15+ year-old system springing a leak due to the higher pressure a combi boiler puts it under. The cost is about equivalent (replace conventional boiler and HWC, vs fitting a combi boiler and re-routing pipework to support it). Are combi boilers cheaper to run? Much less reliable? Quote Link to comment Share on other sites More sharing options...
The Raven Posted April 19, 2012 Share Posted April 19, 2012 If it was my house id go combi. Like with most things you get what you pay for, i just paid 4k for a full heating system in my rental however the boiler has a 5 year warrenty on it. Make sure they lag the vent pipe! Most of these combi break downs are due to the steam becoming frozen in the vent pipe and backing up, ive seen two do this winter alone. Quote Link to comment Share on other sites More sharing options...
TokyoRich Posted April 19, 2012 Share Posted April 19, 2012 Im having a new Combi fitted today! Will let you know, its a Valiant EcoTec Pro 28KW. Essex boilers are doing it and total cost is just over 2k (British Gas wanted 4k after their special offers and discounts). Quote Link to comment Share on other sites More sharing options...
probrox Posted April 19, 2012 Share Posted April 19, 2012 I think it depends on the plumbing you have in the house. I have a conventional boiler and would probably replace with the same so that I didn't have to mess around changing the shower etc which wouldn't be compatible with a combi. Quote Link to comment Share on other sites More sharing options...
Colin-mkiv Posted April 19, 2012 Share Posted April 19, 2012 My combi is getting its annual service as we speak! Combi is better than the old style syestems. Just make sure the one you get is top notch. Dont try and scrimp. Quote Link to comment Share on other sites More sharing options...
stevie_b Posted April 19, 2012 Author Share Posted April 19, 2012 The shower wouldn't need changing: the shower's actually a high-pressure one and so having a combi would simplify it a bit (no need for the dedicated shower pump that we have at the moment). The thing that's holding me back from a combi is the age of the radiators and the connecting pipework (15 ish years old). Also, with a combi, are you limited as to what facilities you can use at the same time? Presumably I could have a shower whilst the washing machine (which is a modern cold-feed only model) was on, or would the demands of the washing machine kill off the incoming water pressure that the boiler needs? Sorry if that doesn't make sense, I'm trying to muddle through various things people have told me. Quote Link to comment Share on other sites More sharing options...
Digsy Posted April 19, 2012 Share Posted April 19, 2012 Just out of interest, how do boilers go when they "pack up"? I've had a conventional boiler in my house since 1996 and (touch wood) its going OK but most parts in the burner assembly have been replaced as those bits are cheap as chips compared to a whole new boiler. Mine has had new motor bearings, a whole new motor, new pump and oil feed pipe, fire valve fitted, oil control valve solenoid, together with the usual regular nozzle replacements. Apart from the igniters, control box and fan assembly there's not much more to the burner side of things. Do they actually spring a leak in the water circuit or something? Quote Link to comment Share on other sites More sharing options...
stevie_b Posted April 19, 2012 Author Share Posted April 19, 2012 Digsy: I think the control board on mine has got a fault (possibly electrical, hard to say without diagnosis tests). The pilot light comes on, and you can hear the clicking as the spark tries to ignite the main burner, but I think the control board is preventing the gas from flowing into the main burner, hence the spark is sparking in vain. It is also showing signs of corrosion of some parts although I don't this has caused it to stop working. It would be a simple problem to fix if the manufacturer still sold the part, but I'm told they don't. Quote Link to comment Share on other sites More sharing options...
probrox Posted April 19, 2012 Share Posted April 19, 2012 When mine broke down last year it turned out to be a 25p fuse on the circuit board, i was relieved to say the least. Quote Link to comment Share on other sites More sharing options...
Jamesy Posted April 19, 2012 Share Posted April 19, 2012 just had a combi fitted last month after mine packed up. everything cleared out the airing cupboard and its the best move we made! go for it Quote Link to comment Share on other sites More sharing options...
Digsy Posted April 19, 2012 Share Posted April 19, 2012 It would be a simple problem to fix if the manufacturer still sold the part, but I'm told they don't. I guess that would do it. I should have said that mine is an oil boiler. Luckily parts for the burner seem to be pretty universal and comparitively simple to get hold of. Quote Link to comment Share on other sites More sharing options...
Colin-mkiv Posted April 19, 2012 Share Posted April 19, 2012 The shower wouldn't need changing: the shower's actually a high-pressure one and so having a combi would simplify it a bit (no need for the dedicated shower pump that we have at the moment). The thing that's holding me back from a combi is the age of the radiators and the connecting pipework (15 ish years old). Also, with a combi, are you limited as to what facilities you can use at the same time? Presumably I could have a shower whilst the washing machine (which is a modern cold-feed only model) was on, or would the demands of the washing machine kill off the incoming water pressure that the boiler needs? Sorry if that doesn't make sense, I'm trying to muddle through various things people have told me. We do tend to lose pressure if more thgan one water point is running yeah, doesnt really bother us. Just dont turn the tap on full when you're washing your hands after using the loo, cos when the cysterns filled up and if the tap is still on you'll get soaked when the pressure comes back.... Quote Link to comment Share on other sites More sharing options...
keener Posted April 19, 2012 Share Posted April 19, 2012 I'd go the combi route. Why spend money heating a whole cylinder of hot water when it might not even get used and just cool down again? I had a combi in my old house which was great. No tanks in loft, hot water cylinder etc and it just came on as you need it. I had no problem with running heating, shower and washing m/c at the same time but I did over spec the boiler. We basically figured out how big it need to be then went for the next model up. It was only a matter of £20 or so more and I always believe in oversizing things like that so you have extra capacity should it bee needed in the future and so it doesn't have to work so hard for the system as it stands. If you're worried about the pressure in the pipes is there a way of pressure testing them first? Quote Link to comment Share on other sites More sharing options...
Shane Posted April 19, 2012 Share Posted April 19, 2012 I am really surprised at the comments in this thread. When I saw the original post I thought it would be an overwhelming stick with conventional response, but no. I hate combi boilers and have had tussles with a few now. I have also found that many so called plumbers dont really know much about them and if you are lucky enough for them to have the fault finding flowchart to follow when they come out, they are stumped if its something that fails outside the scope of the flowchart and they have to do real fault finding. My old boiler failed and I went out of my way to find a conventional one that I could fit and forget and if needed fix without the worry of control boards, flow switches, flowmeter sensors etc. Like you I have old plumbing and a HW tank all in excess of 26 years old so I was worried about upping the pressure. I reckon for what I lose on my conventional boiler's lack of efficiency compared with a modern condensing combi, I make up for in the summer by heating my water on cheap nightrate electric rather than gas. A well lagged tank loses little heat during the summer. My son had an early potterton lynx and my god that was just a complete heap forever going wrong, and we replaced that with a cheapie from Wickes which was ok for about 2 years and then one of the flowswitches failed, followed months later by the gas solenoid. My daughter has one that sounds like Ferrari, (but it's not) and last year she had a sensor fail and it took a week to get a replacement although it was only 18 months old and she had a maintainance plan on it so she was without water or heating for a week during winter with a new born baby in the house. No thanks, at least if my heating dies I can still have hot water from my immersion. IMO, conventional FTW. Quote Link to comment Share on other sites More sharing options...
dandan Posted April 19, 2012 Share Posted April 19, 2012 I've got an oil fired combi (Worcester Heatslave) that is sixteen years old and still ok. I have replaced jets, burner motor, diverter valve motor, baffle plates etc but it is still fine. I am told that is the main water tanks splits then that pretty much writes it off as it is an uneconomical repair. I'd have to weigh up doing part of that repair myself before deciding to bin the whole thing. This model stores about 45litres of water so in some ways it isn't quite a true combi - I think this is the case for most oil fired versions though. It will easily supply a very hot shower at 25litres/minute at 3 bar which is a lot. I'm actually waiting for some restrictors to arrive to throttle the showers down to more like 10litres/min as they're a bit OTT at the moment. For me, one of the downsides to a combi is the need/desire to over spec them slightly when compared to the true heating load of the house. This seems to be common practice to get the hot water supply to be ample. The trade off is short firing cycles for the boiler as the heating output is a little too high - a long steady burn is a lot more efficient and this is one advantage of a proper cylinder based system. Another disadvantage is that it is hard to integrate solar hot water and other heat sources like wood gasification or back boilers to a combi system. A tank makes it easy as you have a natural neutral point to connect everything to. I'm actually in the process of speccing up a complete new system with a 15kW gasification boiler stove, and an array of solar tubes to reduce my reliance on oil. It's a lot of money to spend up front so I'm working out what sort of payback periods I'm looking at for various options. Quote Link to comment Share on other sites More sharing options...
bambisdad Posted April 19, 2012 Share Posted April 19, 2012 Our plumber who has done a lot of work for us absolutely hates them. He says that he would choose a condensing boiler every time. Quote Link to comment Share on other sites More sharing options...
j_jza80 Posted April 19, 2012 Share Posted April 19, 2012 Our plumber who has done a lot of work for us absolutely hates them. He says that he would choose a condensing boiler every time. Condensing is a totally different thing to combi or conventional Combi boilers are crap compared to conventional systemS. Most combis can only flow circa 10l per minute, a conventional cylinder can easily flow 3-4 times that amount if required. Some of the very expensive combis can flow upto 20l per minute, but you'll be looking at circa £2k for the boiler alone. An unvented system or a pumped conventional system are your best options. Plumbers like combis because they're easy to fit. Quote Link to comment Share on other sites More sharing options...
jsnlvxr Posted April 19, 2012 Share Posted April 19, 2012 combis save space but when the go wrong your stuffed.no heating or hot water unless you have a electric shower. i would defo go pressurised cylender so very good hot water but back up immersion and stick with conventional or system boiler. not cheap though. but the best way!! Quote Link to comment Share on other sites More sharing options...
jsnlvxr Posted April 19, 2012 Share Posted April 19, 2012 and combis will only deliver the stated flow rate if the incoming mains pressure is good enough. condense is always best run inside too if possible. saves it freezing in the wnter Quote Link to comment Share on other sites More sharing options...
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