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
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
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
3 Can I add thermostatic rad valves throughout? If I want to
change them from the yorkshire type, will I have to change the
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
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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
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
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
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
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
- 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.
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.
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
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.
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
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.
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.
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.....
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
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.
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...!
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