Heating Questions and Answers
Some of your questions about boilers, boiler installation
and other heating problems answered.
There is no longer any support for your heating problems from me via e-mail or phone. Please contact a local plumber.
Is a combi right for me?
What size boiler?
Sealed system water pressure low
Instruction manual
Can I change a radiator?
Is my gas pipe large enough?
Oil fired cooker
Heat loss calculations
Pipe sizing query
Gas or oil?
Boiler price
Wall flame oil boiler
Should I go for a combi?
Combination boiler hot water flow rate and reliability etc
Combination boiler problem 1
Combination boiler problem 2
Combination boiler and shower
Adding a larger radiator
Expansion tank with hot brown water in it
LPG or oil?Is a combi right for me?
David
Your site is great...but can you help? I am wanting to upgrade the gas hot water boiler (which is situated above my bath) and the gas central heating boiler which is hidden in my bedroom) with a new gas combi boiler in the kitchen. I am confused....am I thinking along the right lines??? I have assumed that as I live in a tiny one bedroom self contained flat in purpose built block that I only need a small boiler. Can you recommend any good plumbers in Peckham SE London? Hopefully you will have a moment to reply... many thanks
Reply:-
The combi boiler is the ideal solution for heating and hot water in your situation. The heat output form a combination boiler is large when in central heading mode but the better quality more sophisticated boiler will adjust its heat output automatically to match the heating load. Hot water should not be a problem provided you have good mains pressure.
Plumbers in Peckham! Sorry, don't know any, never been past Swindon!!!
No liability can be accepted for advice which is given in good faith.
Question:-
I would be grateful if you could advise what capacity boiler I need to heat and provide hot water for a 4 bedroom 2 bathroom house. I also want information about which floor standing slimline boilers as I need to fit the boiler in my kitchen. Can a slimline boiler be housed in a kitchen unit, and if it can does the door need ventilation grilles and how many. What are the dimensions of slimline boilers you would recommend? Friends have mentioned Ideal do a slimline boiler. Could you advise re prices also?
Many thanks
Reply:-
It's some time now since I last install an Ideal Mexico Slimline but from memory I believe they have a heat output of 55,000Bthu’s this may not be enough for a four bedroom house. Depending on many factors the exact size of the boiler output is hard to say but probably in the region of 60,000-70,000Bthus. Building an Ideal Mexico Slimline into a unit with a door on the front would not be allowed. Have you considered using a wall mounted boiler but at low level. As long as you can comply with the manufactures clearances around the boiler it could well be possible to build one into a base unit.
DAVID
No liability can be accepted for advice which is given in good faith.
Sealed system water pressure low
Question:-
I have just moved into a new house, with a combi boiler. The boiler has a pressure gauge, and over the last month the pressure gauge has got lower and lower until now it is in the red section. Any suggestions??? The boiler was moved about 3 feet before I moved in. Also, I'm bleeding air out the radiators at the moment - although it’s too early to say whether more air is getting in. My main confusion is why the system isn't topping itself up as required when it appears to be lowering so slowly.
Cheers
Many thanks
Reply:-
Combi boilers are connected to sealed systems and there is no automatic top of the water pressure. If you bleed air from the system or drain water for any reason you will have to top up with water manually. This is often done by a flexible filling loop near the boiler; do not over fill usually 1bar is enough. Some boilers have the filling loop built in but it will still require manually filling. Consult the user /installation instructions. Do not run the boiler with very low or no pressure in the heating system. You should check for small leaks but it may be that once all the air is removed the pressure will hold.
DAVID
No liability can be accepted for advice which is given in good faith.
Question:-
I am looking for an instruction manual for the boiler in my new house - it was manufactured by STYX and I cannot programme it without some instructions!
Any ideas?...
Reply:-
DAVID
No liability can be accepted for advice which is given in good faith.
Question:-
I have a combi boiler (alpha ocean boiler 240/280) and I just wanted to know if it is ok to change a single radiator to a double radiator, I have 3 double and 3 single at the moment, and will it make much of a difference? Will it effect the pump? Thank you for your time.
Reply:-
No problem at all, the combi boiler will have more that enough capacity to cope with a double panel instead a single.
DAVID
No liability can be accepted for advice which is given in good faith.
Question:-
I currently have a 15m pipe running to entire length of the house from the gas meter to the gas fire. It is not protected with anything, and need to know if it should be? Also we have been told that it should be 22m to comply with current regulations. Should we have this upgraded?
Reply:-
A 15 metre straight length of 15mm copper pipe should be adequate for a gas fire unless there are a large number of bends or it is also supplying another appliance. A CORGI registered installer should be able to confirm this. They would also be able to say whether the pipe is adequately protected. Without seeing the installation I am not able to comment further. I can only suggest that you obtain further advice from a local installer.
DAVID
No liability can be accepted for advice which is given in good faith.
Question:-
Hello David, can you tell me where I can get spares for Duchess Cookers that used to come from York Park at Amersham? I think they have sold up. Who bought them up and where did they go? I need hot plates, baffles and fire-bricks for the pressure jet burner.
Reply:-
Can't help much with this one I'm afraid. You could try OFTEC www.oftec.org, probably best to ring and ask on 0845 65 85 181. Their equipment directory lists three cooker manufacturers www.trianco.co.uk www.aga-rayburn.co.uk and www.waterfordstanley.com
Good luck
DAVID
No liability can be accepted for advice which is given in good faith.
Question:-
I have recently moved into a 1920s house, which needs the boiler replacing.
I have gone through the calculations for the radiator requirements and they match closely what were in existence.
My quandary is that a Corgi engineer who was installing a gas fire, advised that I would need a replacement boiler with an output of 100,000; 120,000 BTU;s/hr.
The calculations for just the radiators give a requirement of 67,000 BTU;s.
I assume I need to add in say 5kW (15,000 BTU;s) for the heating coil, and there are presumably some losses in the pipes and inefficient /;lime scaled; radiators, say 10% or 7,000 BTU;s.
This adds up to 89,000 BTU;s.
What I notice from the ads for boilers is that the price rises steeply above say 90,000BTU;s.
Are my figures wrong? Do I need a bigger boiler?
Thanks for your help. Your web-site enabled me to work out that I need a floor mounted replacement boiler as my wife refused to lose the airing cupboard.
I assume that retaining the tank allows me the option to use the immersion to heat water, in case the boiler is off or not working?
Reply:-
Your calculations seem reasonable to me.
All boilers are range ratable so that a nominal 100,000Btu boiler can be adjusted to meet the heat load requirements. Many are fully modulating and will automatic adjust to the heating load. But if cost is your prime concern and you are confident about your calculations go for the 90,000Btu boiler.
Your hot water cylinder can of course, have an immersion heater fitted.
DAVID
No liability can be accepted for advice which is given in good faith.
Question:-
David,
I need a replacement 100,000 btu boiler and have been told by British Gas
that the 22mm pipes to it need to be replace with 28mm, is that correct?
Unfortunately I am in Newbury so a bit outside of your area.
Think you have a very good website.
Reply:-
Yes it's reasonable to suggest that the 22mm pipe work is not sufficient for a
100,000Btu boiler. As a rule of thumb any output over 60,000Btu's requires
that the heating flow and return pipe work be in 28mm.
DAVID
No liability can be accepted for advice which is given in good faith.
Question:-
NEW C/H BOILER REQUIRED (CURRENT GAS ONE IS KNACKERED AFTER 19 YEARS) NOT SURE TO KEEP GAS OR GO DOWN OIL ROUTE!!4 B/R HOUSE SHOULD HELP WITH BOILER SIZE REQUIRED.
CAN YOU HELP?
Reply:-
Very few people choose to have oil if natural gas is available. Gas boilers have a number of installation advantages, smaller size, more flueing options, quite operation etc.
For a four bedroom detached house you would probably require a boiler in the region of 65,000Btus or 21kW.
DAVID
No liability can be accepted for advice which is given in good faith.
Boiler price
Question:-
Can you give a price for a Danesmoor 45/75 oil boiler? Boiler room installation type in either Warmflow 150/200 or 120/150 .. or possible other make
Reply:-
I'm sorry but I'm unable to give prices for boilers. My business is supply and installation. You could try:- www.plumbcenter.co.uk www.ptsplumbing.co.uk
DAVID
No liability can be accepted for advice which is given in good faith.
Question:-
Sorry, but the service and maintenance of wall flame boilers is not something that I undertake and am not able to give you any advice in this matter.
You may be able to get some info from www.oftec.org (Oil Firing Tech. Assoc.)
DAVID
No liability can be accepted for advice which is given in good faith.
Question:-
Please advise on the following:
I have a twenty plus year old galvanized steel water tank with an immersion heater tank with all the complicated network of piping system inside our airing cupboard in our flat. They are starting to leak and looks like it's time to change the whole system including the original boiler.
Would it be efficient to take out all the above, cut away all the piping in the cupboard and replace the whole lot with a combination boiler? If so, what is the estimated cost of labour and materials, i.e. the whole project?
Much appreciated.
Reply:-
If you have a galvanized hot water tank that is showing signs of leakage I think that it is well over due for replacement. A combination boiler is probably the best way to go but it does depend on the type of property but they are ideally suited to small flats.
I guess that if your talking of a combi and six rads should be round about £…………but there are lots of variables so could be less but probably not much more.
DAVID
No liability can be accepted for advice which is given in good faith.
Combination boiler hot water flow rate and reliability etc
Reply:-
Hot water flow rate is the biggest draw back to combi boilers but how much of a problem, if at all, depends on a number of factors.
Reliability does not seem to me to be of concern these days, as an installer it's just as important to me as to my customer. I very rarely get call backs to combi’s that I've installed. You can of course just replace your boiler with another keeping the hot water cylinder and roof tanks and use a condensing boiler, but if not already fully pumped the system will need upgrading.
Reply:-
The important consideration is flow rate, i.e. litres per minute of hot water at 35degrees C (minimum). It is important to have good mains pressure and to have the cold supply to the boiler as the first tee of the rising main. But clearly with any mains fed systems the more you draw on the supply the lower will be the working pressure and this will affect flow rates at the hot taps etc. In practice this is not generally too much of a problem, I'm sure you will appreciate that watering the lawn, flushing the loo and showering all at the same time is best avoided but with good installation practice pressure reducing effects can be minimised. The two alternatives to the combi are a conventional system with roof tanks, hot water cylinder etc or an un-vented hot water cylinder and boiler. Un-vented cylinders are also mains feed.
Regards
DAVID
No liability can be accepted for advice which is given in good faith.
Question:-
I am having an overflow prob. from the expansion tank. There is a constant drip into the tank which suggests the washer needs replacing in the cylinder of the ball cock - something I have done in the past re the cold water tank . I believe the inflow comes from the hot water cylinder and am not sure how this is controlled i.e. if I remove the ball cock to insert a new washer will water gush into the expansion tank ?? The cylinder in the airing cupboard is about 10 yrs old.
Any advise you could offer me would be appreciated. Cheers!
Reply:-
To rewasher the ballvalve in the expansion tank you must first turn off the main stop cock. (The expansion tank ballvalve is feed by mains cold water). This is often under the kitchen sink etc. Once you have turned it off, check to make sure but pressing down the arm of the ballvalve. If no water flows proceed with the rewashering. Good luck.
DAVID
No liability can be accepted for advice which is given in good faith.
Combination boiler problem
Question:-
Great to see the possibility of free advice! Having said that I understand
if you don't reply because a) tedious question, and b) no money earner.
I moved into a flat last week, which has had a new boiler fitted (Worcester
24CDi). For the first couple of days I saw the lights flashing, but I was
busy on my way to work, and paid little attention. After a weekend away, I
programmed the timer to heat up water in the morning for a shower. Water was
freezing, lights still flashing on boiler, programme is still in the timer,
but pressure shown as zero. I forgot about it, had a shower at the gym, and
looked at it last night.
I read on the internet about a plastic T shaped key to pressurize the
system. Last night I turned this clockwise say 20 turns, expecting pressure
to rise but nothing. Turned off and on as I had done previously with left
most knob. This time no power light as if no electricity going into the
boiler. Cannot see pilot light either.
Power to the boiler appears to come from the timer which is still active.
So...Is power reliant on sufficient pressure? Do I need to turn the key the
other way? Should I proceed with this myself? Does it sound like an
electrical issue rather than plumbing?
Cold water pressure is in general good despite being 3rd (top) floor.
Washing machine also wants to take hot water from boiler.
Any help greatly appreciated.
Thanks
Reply:-
Sorry to hear about your troubles with the 24Cdi.
The key you insert into the boiler is only the link from the mains cold
water to the heating circuit. It should be inserted and turned through
90degrees only and then you can pressurize the system by turning a much
smaller grey knob just to the right of the key. Do not go above 1bar. This
procedure is in the installation instruction that should be with the boiler.
There is no permanent pilot light, electronic ignition.
The flashing light indicates that the boiler needs resetting and this is
done by pressing the small red button on the fascia panel but do not do this
until you are sure the system and boiler are full of water.
The programmer only controls the heating, power for hot water should be
permanently on provided the left control on the fascia, the hot water
thermostat is off the min/off position.
Check that the electrical isolation switch is on and the 3amp fuse okay.
All of the above can be found in the user installation instructions that are
required under gas safety legislation to be left with the occupier. If you
do not have a copy it can be downloaded from www.worcester-bosch.co.uk
You should also have a Benchmark logbook that will give details of the
installer who you may wish to contact.
Regards
DAVID
No liability accepted for advice which is given in good faith.
Question:-
My hot water boiler will not come on. The digital display box that displays the time and date of when I want it to heat water is not displaying, it is blank as if a power cut. I have checked the fuse this is still working. Without the display box working this obviously will not activate the water boiler? Any idea what the problem is? Thank you for your help.
Reply:-
Sorry to hear about your programmer problem. It's difficult to be sure but if the unit is receiving power and the display is blank it will probably need replacing. You do not say whether it's an integral part of the boiler or separate from it. If it's part of the boiler it is not a diy job but if it's separate they can usually be exchanged with a new one of the same manufacturer and type quite easily. But if you have any doubts contact a qualified electrician or CORGI register installer. Mains voltages are present in all of these units.
DAVID
No responsibility can be accepted for advice which is given in good faith.
Question:-
Very much appreciate any advice you can give on my Gloworm swiftflow 100 combi boiler.
In summary, boiler does not fire up when I switch the tap on. Central heating is fine. I have had 2 different plumbers(corgi registered) both ripped me off by installing parts they thought were at fault and I still have the problem. They have replaced, User PCB, safety valve assy(don't know why?) and water pressure switch. What else could it be? so at least have an idea when I get the next repairer.
I am beginning to lose faith with plumbers. And the missus is doing my head to get it fixed!
I live in the Midlands which is outside your area
Thanks for your time.
Reply:-
Sorry to hear about your problems with the boiler and plumbers!
I'm not too familiar with the Glow-worm Swiftflow but I expect that in common with most combi's there is firstly a flow switch that should activate when you turn on a hot tap which will in turn activates a diverter valve. This puts the heat output of the boiler into producing hot water. Suspect the flow switch or diverter valve.
Or visit www.glow-worm.co.uk who have a technical helpline and Heat Call service.
DAVID
Question:-
Dear David. I purchased a house that has an electric shower installed, a Triton T80. It is not working and needs to be replaced. I have been told that the wiring is also not too good and should be upgraded to take an electric shower.
I have recently had gas central heating installed with a combi boiler Vaillant ecomax.
Am I right in understanding that I can run a shower from the combi boiler and not have to go to the expense of buying a Triton shower. If so is there a down side to this option. It makes sense to use the combi boiler that is already there rather than install another one. I do not have a hot water geezer or a water tank, the cold water mains feeds directly into the combi boiler.
Any help or advice would be appreciated. regards. John Smith.
Reply:-
Combination boilers provide you with mains pressure hot water and if this is used in-conjunction with mains cold water this results in a very good shower. There are many shower mixer valves designed for use with a combination boiler i.e.. Mira 415. There will be additional plumbing for the new shower but you won't need to upgrade electrics etc.
Reply:-
Drain the system, remove the old radiator, cut the pipes just about half way up, hang the new radiator, fit the valves, use four elbows and a short piece of pipe to make the new connections. I doubt if you will have enough length in the pipe between the floor and radiator to bend a set so use elbows either soldered (will look neatest) or compression (no need to solder).
DAVID
Expansion tank with hot brown water in it
Reply:-
System boilers do not have expansion tanks. But whatever type of boiler you have there shouldn’t be hot water circulating through the expansion tank. If it continues for any length of time the aerated water will rust radiators and cause many other problems. Call back the installer and explain what you have found.
Regards
David
No liability for advice which is given in good faith.
Question:-
I have had so much conflicting information that I do not know which way to
turn. I have a 4 bed semi and have had my Gloworm (LPG) back boiler
condemned.
I would like to keep the outset gas fire type but cannot find one I like.
I am now looking to change to oil. A Grant boiler house model looks good. My
garage is only 24" away from the house. I have had a quote for £2500 to fit the boiler,
tank and pipe up. Or should I stay with an LPG gas boiler. I have up to
£3000 to fit a new boiler. The old boiler was costing £700 per year to run
and info I have had off people is oil will cost £300 and LPG £450. Also is
there any grant aid I would be able to claim? Please help I am at my wits
end and I am getting verbal from the wife! Many thanks,
Reply:-
Most of my dealings with LPG are because people find it too expensive to run
and come to the conclusion that oil is the best alternative. I have little
doubt in my mind from my customer’s feedback and figures that occasionally
appear in the trade press that oil certainly has lower running costs that
LPG. Exact figures are difficult to give but suffice to say that after
on-peak electricity LPG is the most expensive heating fuel. Payback time
4-5 years.
£2500 sounds a fair price for a new boiler and tank etc.
Some manufacturers offer a cash back deal, not much, usually about £75.
How about a log burner for the lounge?
Regards
DAVID
NO LIABILITY IS ACCEPTED FOR ADVICE GIVEN.
David Kearns © 2004