Which Boiler

[diyhelpme]

Hi - I'm after advice as to which boiler make/type/size I should consider as a replacement.

Current boiler 18 years old - 60000 btu I believe - with room stat at 20 deg boiler never shuts off in winter - ok at 19 deg - maybe stat fault?

I was thinking of a combi condensing type - but house is 4 bed and 16 radiators - though all bedrooms with stat valves and rooms hardly used like dining room downstairs toilet, utility room are turned down - as are bedrooms and although we use the shower mostly, we use dishwasher a lot and large american top loader washer is used every other day - so I'm thinking of staying with hot water storage tank as I do not want to experience poor flow rates of hot water.

So - what size boiler - all rooms 12ft sq, 5 downstairs 4 upstairs - we are also thinking of extending with additional 3 bedrooms.

I was thinking 80000 btu, maybe 100000 btu if we did extend.

What boilers should I consider?

Any advice appreciated.

 

[croydoncorgi]

On the face of it, your boiler may well be undersized for the load - so it WILL run all the time the heating is on. Probably nothing wrong with the stat if it cycles on and off at 19 degrees on the room stat.

Something like a Keston C40 or a Worcester 30CDi Conventional would do, maybe. You need to do a proper heat calculation based on room sizes etc. Also, bear in mind that it's better to be over-size rather than under-size with a condensing boiler

 

[diyhelpme]

Thanks for the advice - can you suggest a good site to get the room/radiator/kw calculations?

The radiators get really hot (too hot to touch really) - they are the normal pressed steel 750mm high or so with double convectors - so I was wondering if I should also consider fitting better radiators in the rooms that need more heat - can you advise any?

Looking at what is posted here so far I had thought a boiler would be in the order of £600 to £900 or so - what should I expect the fitting charge to be?

The current boiler is a balanced flue type fitted in the garage - which brings me onto another question - I presume I do not want a boiler that cannot use my existing timer/control unit that is inside the house.

The Worcester looks pricy but affordable if needed, the Keston is out of my price range.

Currently my system has pumped CH and HW using room stat valve and cylinder stat to control them. Cylinder has normal header tank and is indirectly heated - I think that is what you call it when the tank has a heating coil of pipe inside through which boiler water passes to heat the tank water.

Anyhow - the Worcester you mention - is this ok for my application?

Looking in B+Q - I realise that the Worcester is generally highly rated but could you offer any observations on the Ravenheat Condensing Boilers - at £450 they are quite a saving.

Kind Regards

 

[kevindgas]

wouldn't touch ravenheat with a barge pole useless B&Q crap spend a little more and get a decent boiler

 

[ACOperson]

Your budget for a boiler extends to £900!

For a house of that size you should be looking to spend a minimum of £900 and get at least a 35kw condensing system boiler using a thermal store or unvented system if your water pressure is up to it, or keeping your cylinder if it meets your current hot water demands.

It is an expensive option, but think about how much you use the heating and hot water. Even if the system costs £3500 in total, if spread out over only 5 years it'd work out at about £1.90 per day, and it will last more than 5 years anyway!

I would reccommend that you look at something from Worcester or Glow-Worm as a minimum, but preferably frm either Keston, Vaillant, Boulter or Viessmann (in ascending order) If you scrimp and save on the boiler, or on the installation you will end up paying for it later!

 

[Agile]

The Ravenheat is capable of adequate service as long as its properly installed on properly cleaned system. It is however perceived as a budget boiler.

Look at the guarantee on their Band A boiler, I think it could be three years.

You budget is far too low for a proper upgrade. Have you taken into account TRVs on all your radiators, proper controls which for a larger house means two controlled heating zones? Replacement cylinder?

I would suggest more like £1300-£1800 just for the materials.

You have not mentioned installation? Just how are planning to deal with that? As you will know the boiler bracket, gas supply, flue and commissioning have to be carried out by a CORGI registered engineer.

Tony Glazier

 

[diyhelpme]

Thanks for some very good advice.

The issue for me is what to buy - too much choice!

The "budget" boiler does indeed have a 3 year warranty - but I'm tempted to spend more for a "better" boiler and your experience/advice helps me to decide - I'm hoping the advice is based on reliability and ability to suit my needs rather than because of the brand...though I understand you would expect a "branded" boiler to do better.

As for size - I've got TRV's (sorry I called them stats - obviously not a plummer) and as for installation - I've asked what to expect to have one fitted - so yes I intend to use a Corgi gas fitter.

I live in an area where there is no "furring" or deposits from water - so I was hoping to keep the existing hot water cylinder. System is all 15mm copper pipe joined together with yorkshire fittings (soldered to me) and I know its in sound condition as I have altered many of the radiator positions and both cutting into pipework and draining of the total system the water is dirty but no deposits.

But - a friend has suggested a baxi with hot water storage (thermal store I think) - a condensing combi which he had installed in a 7 room house let out to students and claims it work fine - any comments - I'm going to see it and the hot water flow because I had counted out a combi for earlier reasons. My last house had a baxi (cast iron) and it was very reliable.

On another tack - the condensing type - I like the design of the Viessmann with its stainless steel condenser. I realise stainless steel does not conduct as well as aluminium - but if they both have the same efficiency (A) then is stainless not best?

Zoned control - was thinking about that - we live in 1 of 2 rooms downstairs - it would be nice to be able to pick which room controls the temperature - what would you suggest?


Thanks again for the help - I've a few months to decide then get some quotes.

 

[croydoncorgi]

ACO: why do you say

get at least a 35kw condensing system boiler using a thermal store

.

IMHO, thermal stores of any kind and condensing boilers CANNOT ever be compatible due to mismatched operating temperatures. Before you respond, check out the 'condensing temperature limit'. You will find it's specified for ANY condensing boiler at 55 or 56 degrees. Above that, the boiler CANNOT condense, so will not achieve anything like its rated efficiency. Heatstores have to be at around 80 degrees to be any use.

DIYHelpme:
Viessmann make nice boilers. But the only 'affordable' model (Vitodens 100?) has had all the good stuff taken out to keep the price down! I wouldn't worry about stainless steel being a poor conductor (compared with what?). The key question is wall thickness and a S/S HX has quite thin tubes. The other real issue is will it last? Viessmann guarantee theirs for 10 years, I think.