I've finally done the calculations using Mysons heatloss manager, and the figure it is giving me is 32kw (inc water). I have included rooms not yet developed (but will be in a couple of years). Checked on
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- boiler database and it lists 32 that have output ratings of between 32Kw and 40Kw.
Would anyone be so bold as to recommend one, and maybe give reasons why?
My plan is to decide on which one, and between now and next summer, put in all new pipework (myself.... don't laugh). Once the weather is being kind, I plan to fit new rads (with trvs) based on the heatloss managers data, and then get a corgi plumber in to commission (he is a friend so will be checking the work throughout anyway),
Sorry - should have added - it will be installed on the ground floor - and will eventually need to pump water to a loft conversion. Would like to think a combi (with no hot water tank).
Got a big old house (in the process of upgrading insulation etc), no kids (only two of us) so not a lot of call for hot water except during the morning rush!
Do you have the figure for the hot water Simon? IIRC, the Myson program calculates it as though there is a gravity hot water cylinder and puts in a few kW for it.
In most system designs nowadays which use a cylinder or heatbank for the HW, you arrange for the boiler output to be directed to that and away from the heating when required. The cylinder is able to absorb energy more quickly with a pumped arrangement and you can buy a cylinder which recovers quickly. In other words, you can leave the HW requirement out of the calculation and just look at the heat loss in the house.
It's certainly worth going for a .condensing boiler if you are using this amount of energy. You can easily spot them in the list because they have SEDBUK efficiencies of 90%+ and the conventional boilers have 78-80%. If you are fitting after next April, you will have to use a condensing one anyway.
I have been very happy with my MAN Micromat - a very solid German made product sold by MHS boilers here as the Strata 1 and by Eco Hometec. Not cheap, but an excellent product.
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have a range of models up to 76kW, and in the range you are looking for, 31kW and 38kW. The internal controller modulates the burner and the pump to produce an output from 4kW up to the maximum output, matched to the temperatures outside and indoors using a weather compensating sensor. An optional sensor for the hot water gives good control and very fast recovery. In short it does what it says it does.
I'd still make sure the hot water supply is adequate for a family. You're spending out a lot of money, so worth doing the job properly - especially if you're DIYing much of it, so it's only parts cost. You can never be sure when you might need to sell, and a large house with an inadequate system would put many off, or reduce any offer.
Yes - the Myson throws in 3kw for water - so removing that would bring my total 'eventual' requirment down to 29kw.... It also factors in
20% for 'intermittent correction' (heaven knows what that is!) and 15% pipe losses.
I have also factored in nealry all rooms being kept at 18 degress - when in reality, I suspect there are a few that will never be kept at that temp - as they will be rarely used.
Are there any retailers that sell the Micromat boilers? A quick search found none. Are they well supported..... in the UK? I took a look on the website and although a lot of the data went over my head, they seem to be very well thought out.
OK. Intermittent correction is to cover the case where the heating is run intermittently and to cover extra needed to warm the fabric of the building.
Even so, it's probably better to overprovision a bit anyway - the boiler will modulate down in heating mode. Then if you are going to go for a combi version, you will get better HW performance. Given that, I would probably go for the 38kW rather than 31kW models.
They sell through two distributors in the UK - MHS Boilers and Eco-Hometec. These tend to target the self build market and people who want to buy directly.
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have better literature)
I went into this in a lot of detail and sent both suppliers a detailed set of questions, asking for written responses.
This included warranties, spares availability and prices, service arrangements etc.
Eco-Hometec gave the better set of responses. I also went to visit them to take a look at the products for myself. They have their own service engineers and there was a 5 year parts and labour warranty.
At the time, I was replacing an old Glow Worm boiler, which frankly, in comparison is junk. The build quality was poor, with sharp edges on the metal, bits crammed in etc.
The MAN boiler is like looking at the engineering of a BMW before they covered everything in plastic. The major sub-assemblies such as the pump, burner/ heat exchanger, fan, gas control, (expansion vessel on my model) etc. plug onto a hefty steel back panel through which the water paths run. Any of the components can therefore be easily and quickly replaced if ever needed. The controller is at the bottom away from the heat, and hinges out for easy access to components like the pump in the bottom. The controller itself has chunky electrical connectors onto the wiring loom reaching the rest of the boiler.
I also contacted the product manager in Germany mainly with questions about expected product manufacturing lifetime etc.; what would happen if the distributor went bust etc. I was satisfied with the manufacturer's commitment to the product line - it's their most successful and has won numerous awards in Germany.
I have fitted one Keston C40 (thats 11-40kW). It was OK but in retrospect for almost the same money I would have chosen to get two Celsius 25 units in. Diversity and redundancy added and not much more capital cost. 7-50kW power plant, one entire set of spares on site!
Once you go much over 30kW the pricing of boilers is crazy. I guess the sales volumes are much lower... (also I suspect a touch of the electric shower pricing structure, where more kW make for a much bigger price - same box slightly bigger element).
Also the pipe work losses have to be considered in context. If they are runnning under a suspended ground floor with a stack of external ventilation then take them into account. If they are running around the ceiling void of a post WW2 property then they are effectively zero.
Perhaps what they call an 'intermittent allowance' is extra for warming up. Again I would dispense with this to a certain extent. If you were always expecting to come home to a very cold house on very cold days and then make it all warm quickly then you will need plenty of extra otherwise not.
A few kW for the average water useage is probably fair. Even if it is taken in 15kW chunks every other hour or two.
Its normal practice to install radiators first also its best to put them on the cold side of the room this was you get less thermal differential I.e. less draft from the windows as the radiators warm this air up if the rads are fixed on the cold wall but if you want save pipework and put them on the inside wall you get the could air from the window running along the floor towards the radiator and boy wont you get a cold draft then. MikeS
Are you saying the only type of boiler that can be installed after April next year is a condensing boiler? If so, have you got a link on this? Have I misunderstood your post?
I already have an 'aged' system installed that 'seems' ok'ish - but the house is cold in places where I suspect a guess has been made on the size of rad.
My plan is to lay new pipework (the old stuff looks very old and is 'green' in places - especially around the hot water cyclinder) - following the route of the old. I can do this at my leisure over the winter.
Doing lots of reading and research at the moment (thanks all here!) - and will hopefully enjoy the 'refit' when I decide exacly what I want. Of course, got to get my corgi mate involved - but he works for the council and just doesn't seem to know as much about boilers and CH designs as some of you folks on here!
As I understand it, from next April, all new boilers will have to be at least ?
87% ? efficient which effectively rules out anything other than condensing boilers - expect a rush of discounts on boilers in March and prices of the condensing boiler prices to come down a bit as production volumes ramp up and the initial demand has been satisfied.
appears that there may be some exceptions, but manufacturers are assuming that only SEDBUK Band A & B (i.e. > 86% efficient) boilers will be allowed after April 2005.
READ THE QUESTION YOU THICK SHIT. Simon appeared not to be concerned about the hot water system since it would have little use, there just being two occupants in a large house.
Is that the same thing as thinking it ok to cut plastic pipe with a hacksaw, and wondering why the joint leaks?
Hmmm IMM, field marshall Plowman went fairly quiet I see. Do you know something he doesn't? Does he really think a prospective buyer would check the hot water supply?
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