Long post about boilers and stuff - with too many questions....!

Hi there
My first post here so please be gentle!!
I am looking to do quite a lot of work on the house I am in but am having trouble finding reliable honest advice - so I'm kind of hoping some of you good people may be able to help....
Ok, I bought the house I am in 18 months ago. Built c1870 - traditional 4 bed house - door in the middle (the type children draw), with a 60' long two story barn attached - by an extension of unknown age. (picture on www.thehawthornes.org - the thumbnail photos are small but the full size are getting on for a meg each for any non broadband users!)
The central heating system has 11 rads, with microbore pipe, yourkshire twin end return radiator valves and a floor standing Potterton Kingfisher 2 boiler. The boiler has two seperate circuits, and I have an electronic thermostat fitted on each (an upstairs and a downstairs circuit). I have a hot water tank and a header tank in the loft.
The barn is in pretty good shape - although it does have two tie bars running the full 60' - on the inside - visible running along the first floor. The roof is dry but very old and one of the walls at the top corner needs some work doing (seems to be leaning out very slightly.).
I want to add a loft conversion, and renovate the barn. The loft will have a large bathroom with bath and I'd like a mains water thermostatic shower. I will also need at least two radiators. The barn will need the roof replacing and the wall/structure sorting out. I plan to leave the first floor as one long empty room for now (may convert into a flat in a few years - with electric immersion heater and storage heaters - so no gas). The ground floor consists of a garage at the front, then a 35' long room with an old stable type room at the back. The long room will need maybe 3 radiators (currently has 3 non-working storage heaters).
Ok, here come the questions.....
1    Will my boiler cope with pumping water to the loft for the bath, shower & radiators?
2    Will my boiler cope with the additional strain of 3 rads in the barn?
3    Can I add thermostatic rad valves throughout? If I want to change them from the yorkshire type, will I have to change the microbore pipe?
4    How much of a job is fixing the roof on the barn and how much is it likely to cost?
5    To convert the 35' room, I'd like to plasterboard it - maybe with some sort of insulation on the back of the board - is there anything in the market place like this?
Thanks in advance - I know I am expecting a lot but I'm sure the comments I'll get will be a honest and give me a starting point.
Thanks in advance
Simon
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wrote:

Nice one Colin - thanks - I'll give it a go..... Si
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On Thu, 01 Jan 2004 23:50:35 +0000, Simon Hawthorne

There are several models of this boiler ranging from about 11kW up to 64kW. Can you find the exact model and rating? It should be suffixed with something like CF (conventional flue) or RS (room sealed) and a number ranging from 40 to 220. There should be a plate somewhere with this on and a rating.
You can multiply the model number by 1000 to get to BTUs/hr (a deprecated unit) and then divide by 3412 to get to kW which are easier to work with,

I would guess at the moment that you have a conventional hot water system with a vented HW cylinder and a vented CH primary.
There are then two answers.
For the radiators, you can probably manage from the flow point of view to have radiators in the loft provided that you have a way of raising the height of the feed/expansion tank (the small one) and if you use long, low radiators. I did this in a house that we once had which had this issue and used radiators about 300mm high but about 2m long. There was a head difference (tank height above this radiator) of about 1m.
A mains powered hot water system is a different undertaking altogether. Without changing the boiler, your options are to use a pressurised HW cylinder (basically swap the present one for a sealed and pressurised model) or to use a heat store. A heat store uses a large cylinder similar to a HW cylinder but stores primary heating water at 75-80 degrees rather than the 60 degrees of domestic HW. The cold water to be heated is passed through a stainless steel heat exchanger and water from the store is pumped through the other side of it when DHW is drawn. THis method is effective because the heat exchanger can transfer large amounts of heat from the store to the cold water.

The issue is not the number of radiators - that is completely irrelevant in any heating design.
The important point is the heat requirement of the property - the heating system is basically compensating for what is going out through the outside surfaces.
To work all this out properly, especially in a property such as yours which consists of multiple construction types, is to do a proper heat loss calculation for it.
There are programs for doing this from the radiator vendors - Myson and Barlo have reasonably good ones. Myson's web site is under construction at the moment, but I can send you a copy of their s/w if you drop me an email.
The principle is that you measure each room in metres, surface by surface, accounting for floor, walls, windows, ceiling. You plug these numbers into the program along with the type of material that the surface is - it comes with tables of these and you pick the ones you have; e.g. single glazed window, solid wall etc. Try to be as accurate as you can but there is no need to go to the third decimal place :-)
You plug in a desired temperature for each room (e.g. 21 for a living room is typical) and an outside temperature of -3 degrees. For each room type there are default numbers for the rate of room air changes per hour. If the house is exceptionally draughty, up them a little.
The sofware will give you heat loss numbers in watts for each room. On a new installation, you then pick radiators to equal this heat loss plus a 10-20% margin.
You can do a sanity check using your existing radiators. Look them up in a manufacturer data sheet to determine the output. The figures in data sheets need to be multiplied by 0.89 to give a true output with a boiler such as yours running at 82 degree flow temperature.
If you notice a big discrepancy it can be because the original installer was lazy and guessed the sizes. If you have noticed any rooms to be a bit cold it may be because there is inadequate radiator capacity.
Microbore systems work well, I have one myself. However, one thing that does have to be watched is the water carrying capacity. This is directly proportional to how much heat that can be delivered. It's possible to have a correctly sized radiator which does not give its rated heat because the pipework is not oif adequate size. I had one like this. The solution either involves adding another radiator and hooking back to the manifold, or installing larger bore pipe.
At this point, you should have a good idea about the existing house requirements. Add up the radiator capacities and compare with the boiler output. Conventionally boilers are sized with about a 20% margin over the total of the requirements of the radiators.
Now do the heat loss calculations for your additional pieces. You will have to make some assumptions here regarding insulation. Some of what you are proposing is going to need Building Regulation application anyway and some may as a result require insulation to modern standards. This will make a huge difference to the heat loss and the radiator capacity needed. If the barn has solid walls, it's worth insulating it anyway with Celotex even if it weren't a requirement (I think it is if you will use it for living space).
From this, you can make an intelligent assessment of whether your existing boiler has enough spare capacity.
Don't be tempted to guesstimate. Take a look at one of the programs, plug in different U values for different types of material and you will see what I mean - the differences are enormous.
Having said all the above, there are some additional points to consider:
- This model of boiler is way down on the efficiency stakes. At 65% SEDBUK rating, it could not besold today. You can buy condensing boilers achieving over 90% and will save the corresponding amount of gas. I've done a boiler swap with a similar change of efficiency and am saving 25-30%. If you are planning to stay for a few years, the economics work out.
- Given a modern boiler, you could run the CH sealed. This gets you over the header tank in the loft issue and you can have any radiator you want up there.
- I haven't mentioned combi boilers. This would be another option and you can lose all tanks; *but* you need a very large one to get decent flows of hot water and if you have multiple bathrooms you'll need it. Another option that may make sense dependign on the layout might be two smaller boiler - you would need to cost that out.
- One thing to check before committing to any form of mains hot water system is to check the flow rate at the mains cold tap. A watch and a bucket are the tools needed. If you get less than about 20 litres/minute the results may well be disappointing.

Yes you can, apart from in the locations where there are room thermostats. You can buy TRVs with a microbore compression fitting of appropriate size or a 15mm one and use an adaptor. Often the 15mm ones are cheaper and more readily available. I did this to go from 8mm and you can get a small adaptor which forms a 15mm tail that fits into the TRV after it has been soldered to the microbore pipe.
You will need to run one of the pipes to the opposite end of the radiator. Either it can be run along underneath or behind the radiator. You need a microbore pipe bender and a coil of the soft copper tube. Connect the new length onto the old and run the pipe into place. Try to use formed bends rather than elbows if you can - it reduces the flow resistance.

Pass.
Have a look on the Celotex web site. You will find various solutions to do exactly this for the different types of surface and application notes on how to do the work.

.andy
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Another hint: Google has an archive of this and other usenet groups which you can search for answers to your questions before posting. Also Google 'diy faq' and look at the central heating pages.

So somewhere you probably have 3 zone valves: one for each heating circuit and one for the hot water, and possibly an extra programmer or timer giving separate control of all 3 ciruits - ?

2 rectangular tanks? One big, one smaller, and a hot water cylinder elsewhere (in an airing cupboard)?

The water for the bath & shower isn't pumped by the boiler (actually the boiler's pump) but will come from the cold water storage tank in the roof. You won't get mains pressure from that (in fact you won't get any pressure, as the shower at least will be above the water level of the tank). You'd need either (a) an unvented hot water system (b) a heat bank or heat store, (c) a combi boiler, (d) a negative-head shower pump or (e) an electric shower. There are pros and cons to each, and a google of this group for these subjects will tell you more than you wanted to know about all of them (and of various contributors' preferences for one or other (and for each other :-)).
Some of the options would let you get rid of the cold water storage tank (the big one) from your loft.

It's not the height of the rads that would be a problem (the pump doesn't have to raise the water to the highest point against gravity, as the corresponding flow of water returning to lower levels balances that, and in fact natural thermal circulation assists the flow to higher rads) but you'll need to raise the CH header tank above the level of the loft rads for there to be enough head of water to fill the rads in the first place. You'll have to take care to allow enough height above the tank for the vent pipe, in line with the manufacturer's instructions.

Sounds as if there's a lot of extra space to heat in the barn so the existing boiler probably won't keep you cosy when Jack Frost comes partying unless you're a very good boy with your draughtproofing and insulation. Google 'heat loss' and maybe 'U-value' to find how to calculate how much power you need to heat your house and barn spaces.
I would consider replacing the old boiler with a newer one which could be a lot more efficient (if you chose a condensing model) and would allow you to ditch the CH header tank by having a sealed system. You might choose a combi to give you mains pressure instantaneous hot water for showers and possibly some other uses but you might still want stored hot water for other uses. There has been discussion of it on this group ad nauseam in the past. It might be worth going for a separate boiler for the barn or one larger boiler, depending on the total heating load, pipework runs and how you plan to use the spaces.

Yup, except the room[s] where the thermostat[s for each zone] are - those should have lockshield valves on the rads (so they can be set up by the installer but not twiddled by the users).

You can get TRVs with 8mm and 10mm fittings, or use standard 15mm TRVs with either compression reducing sets onto the microbore, or solder-type reducers. You'll need to arrange flow and return to opposite ends of each rad rather than the type you've got now which (if I understand you correctly) have both pipes connected to the single valve.
-- John Stumbles -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -+ procrastinate now!
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Simon Hawthorne wrote:

Depends on whether its a pressurised system or not. If not, how high the water will go depends on header tank height.
Seeing as you are embarking on majorwork here, I'd be tempted to say a new boiler will not be the worst expense incurred, so budget for one in case. I am not familiar with boiler brands so I can't tell if you have conventional, combi or mains pressure (system) boiler.
I would strogly advocate going to combi or system boiler anyway tho,. simply to get decent hot water pressure round the house - it ends up cheaper than loads of shower pumps anyway! Comnbis unless backed up by hot water stores or rather large in peak output cannot handle more than one shower at a time IME, so ifd you are a house with lots of showers and kids, consider system boiler and mains pressure.

Only an overall heat loss calculation on teh house will tell you what output you need to make sure you can keep the house warm in - say- -5C conditions which is generally what is considered 'worst case'. Others will support the view that of you want a warm cos house, investigiatin existing levels of insulation and upgrading wherever possible if buildig work is to be caried out anyway, is the most cost effective solution.
BTW don't get carried away with double glazing. IME the greatest heat loss in an old house is via the upstairs roof, followed by draughts, followed by the walls, followed by the downstairs floor. Windows and doors, if properly sealed, are not the biggest problem unless vast areas of galss exist (not likely in an 1870 house).

I would say yes, but have little experience with microbore. If you can do it, split teh CH into seperately thermostatted zones instead of TRV's, oherwise TRV's are a cheap compromise.

Depends on whether its a strip and replace tiles felt and battens job - or serious rotted timbers needding carpenters t re-fettle, probably scaffolding, and possibly weatherproofing. Suggest getting quotes from firms in the area large enough to sue if quality poor, and using those as guideline. To felt, tile and batten a medium sized roof is in the 3-8k mark depending on size, intricacy and material quality.

I think so. However you should be using at least 2" of insulation, and it is probably better to line out teh interior with studwork. If you use 12" simply use Celotex, if you have 4-6" use rockowwol (cheaper). Make urse at least 4 times as many cables for TV's phones, lights etc etc are laid as you will actually use. They can be left coiled up behind plasterboard and marked on a plan IN CASE you need them.
You alwasy need SOME of them.

I thnk the rational approach is to
List all teh have to haves List all the nice to haves Put them in order of desperation. Try and assign costs to each one Then shuffle and juggle till you have a schedule of work that you can actually do within HALF your budget.
Do lots of background research, and try and do disruptive things all in one block.
Never start something you cannot fund by an overrun factor of two, as estimated by the trades etc. That way if it does work out twice as expensive, you are not ruined, if it doesn't, there is always another project on your schedule.

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Hi Simon,
Had a quick look at the website, and have to say, I love the kitchen!
Can I ask you where you got the cupboards? The Missus liked then and we are planning a kitchen refit soon! Also, the cooker, is it an aga or is it a look alike gas one? Again, we are looking for something that looks Aga like.
Cheers Mike
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Mike, I saw some cupboards like that in B&Q Warehouse a while back. W.
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Cheers !
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On Fri, 02 Jan 2004 11:35:18 GMT, "Mike Hibbert"

Hi Mike The kitchen was bought from and fitted by a company called Chase Bedrooms and Kitchens in Norton Canes, Staffs. The cooker is a Rangemaster Classic 110 - with a 90 hood - bought from a company in Cannock - cheapest place I could find in the country.... I think Aga owns the Rangemaster..... Regards Si
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No. As it stands, this won't work. The hot water system will be gravity fed from a cistern. The circulating water will be fed from a small expansion tank. Both are probably on the loft floor and would provide no head. The tanks are likely installed in an area you intend to use for the conversion.
To get hot water up there, you should replace your hot water cylinder with a heat bank or unvented cylinder. Your house is basically too big to seriously consider a combi. At the same time, ensure that all cold taps are fed from the mains. This allows you to discard the old large cistern. This all assumes you have good mains pressure and flow rate.
To get radiators up there, you can do one of two things. (1) raise the expansion tank on stilts above the radiator level. (2) convert to a sealed pressurised system. This solution is much better, as it is more reliable and doesn't take valuable loft space. I don't know if the Kingfisher II is capable of sealed operation, though. My mother has a Kingfisher running sealed, but I think it may be a more recent model.

Probably not. The Kingfisher is a fixed output boiler. The output would have been chosen to reflect the likely heating requirement of the house. Unlike a modern modulating boiler, it won't just work harder because of the increased need once it starts going flat out. So, for this reason, (and possibly to enable sealed operation) I'd recommend swapping with a modulating condensing system boiler.

No. You can keep microbore if you like. However, you may have to reroute slightly if you want it to enter at each end. An alternative is to keep the old valves and use inline TRVs on a convenient bit of pipework.

Use Celotex or Kingspan. As you have huge rooms, 50mm is good. If you were a bit tight for space, then 25mm would make a big difference, too.

For such a huge 60' room, seriously consider using fan convectors instead of radiators. These are like fan heaters than run from the central heating instead of electrically. The fan assistance will help circulate the air in the room much more quickly, leading to a faster, more efficient warm up and reduced set back requirement. A couple of Myson Lo-lines should be fine, running off their own zone valve and a programmable room thermostat. The bigger Lolines have 5kW output, a couple of which is probably far more than the room will need after it gets 50mm of Celotex. However, I'd want to grossly oversize such a room to gain rapid warmup due to shear thermal inertia of the air, walls and contents.
http://www.myson.co.uk/pdfs/Fan%20Con%20Tech.pdf
Christian.
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Hi all
Many thanks for all the really helpful posts here. Seems I have a lot of work to do before I actually embark on ripping anything out....! I'll keep you posted on progress and the solution decided upon - although I feel sure I'll be back here with some more questions...!
Thanks again
Simon
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