On Sat, 18 Feb 2006 14:27:51 +0000, David WE Roberts wrote:
Hi,
Explanations first, then questions at the bottom.
I have read the FAQ from Ed (thanks) but it still hasn't really answered
all my questions.
I have a fairly large 1950s 3 bedroom semi - the lounge is roughly 21 feet
by 11 foot 6, with another 9 feet of extension on the end.
The current boiler is an ageing Baxi back boiler in the middle of
the lounge - fitted to a flue which originally has an open fire.
This does central heating plus a hot water cylinder in a cupboard in the
hall.
Although the system still functions, and I am told I could get a
replacement for the hideous fire at the front of the boiler, I would
really like to replace the system completely.
If possible I would like to reclaim the downstairs cupboard for storage,
(or shelve as a proper airing cupboard with a rad at the bottom).
I wouldn't mind losing the tanks in the loft and associated pipework
either.
I currently have an electric shower, but am used to a power shower; I
would like more flow rate than an electric shower if possible.
Currently planning on only one bathroom, and showers are the norm; we very
rarely fill the bath.
Minimum stay here one year plus; possibility of renting afterwards but may
sell.
I have done a rough flow rate calculation using the cold tap at the bath -
I calibrated an orange B&Q builders bucket at 10 litres up to the spout,
then counted 'one and two' etc. as I didn't have two extra hands to work
the stop watch. It takes about 10 seconds to fill a 10 litre bucket
including the turn on time so flow should be at least 60 litres per minute.
I am working full time at the moment so DIY is not an option.
I am now torn between expense and functionality.
The options as I see it:
(1) Replace gas fire and old cylinder; fit shower pump; larger tank in
loft. Move/replace most of the radiators. I will have to fit TRVs, the
radiators are nasty looking and old, possibly slightly undersized. It is
likely to cost more in time/effort to clean and repaint them to an
acceptable standard than to just replace them.
(2) Large Combi - minimum components but limited throughput of hot water.
Since there will be only one shower, and rare filling of bath, this could
well do as long as it can also heat the radiators. (I am not fond of
Combis after a bad experience in a holiday bungalow where I couldn't get
it to supply hot water to fill the bath).
(3) Pressurised system - I lose the loft tanks but still need someplace
for the hot water cylinder.
(4) Heat store - much the same as (2) if I understand correctly.
As an added complication; I have a downstairs toilet at the back of the
main garage, and I keep thinking that this could be extended to make a
downstairs shower room if I can only work out the logistics. The biggest
problem is having to walk through the back of the garage to get to it. The
second problem is that doing it will probably not add much value to the
house. Still, I would like enough spare capacity to work a second shower
if required.
Yet another complication - where to put the boiler. There is plenty of
room in the loft, and this would suit a Combi, but if I have a pressurised
system or a heat store then either the storage also goes in the loft
(where it will need pretty good insulation) or I have a long run from the
boiler to hot water tank (though this may not be a major problem).
Final issue for the moment - I have one small run of pipe under a floor
(under the doorway to the front room). The concrete covering is crumbling.
I would like to get rid of any underfloor piping if possible. Are there
any problems in running a feed down from upstairs (the radiator will be
under the front bedroom radiator).
QUESTIONS
Which of (2) (3) (4) seems the most cost effective solution?
If I go for (3) or (4) can I have everything including the cylinder/heat
store in the loft?
I have had an outline quote of £4,700 to replace everything with another
non-pressurised system; does this seem reasonable? I guess this is (1a) as
I see I haven't included this in my option list :-)
FURTHER RAMBLINGS
The information I have read in the FAQ has been very useful; however it
doesn't include stuff like the crossover point in cost between the largest
combi and the smallest heat store solutions. The area is further
greyed/water muddied by mixed solutions such as combis with small
additional heat stores.
Real world experience of people who have done a similar job recently would
be most welcome.
I'm glad the FAQ has been useful for you.
Even the most modest combi will provide more than twice the flow rate of
your electric shower.
Since you have a back boiler (which I assume was adequate albeit
inefficient) we can be pretty certain the heating load will be satisfied
with 18kW or less.
Without a good look at your house no one can say just where the new boiler
should go. The loft is perhaps the least favourite choice as there are a
number of restrictions if doing the job proerpy which make everywhere else
less hassle.
A properly installed 28kW plain combi sounds like it might be OK for your
needs.
There is not much in cost-wise to choose between a thermal store and an
unvented cylinder (of an appropriate size), since your not diying this
aspect you can go either way.
Stored hot water is likely to add around £1000-£1500 versus the plain
combi option.
A new vented cylinder would probably add around £500. The cylinder being
cheaper to purchase, but the location would best be below the loft.
however once you have adding in a decent shower pump the cost
differentials start to close up between all the forms of stored HW.
The radiator replacements would add around £50-£150 per rad depending on
the quality of the radiator.
HTH
--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at
http://www.diyfaq.org.uk
Gas fitting FAQ
http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ
http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ
http://www.makewrite.demon.co.uk/BoilerChoice.html