boiler/central heating - advice please

[*Lexxy*]

i've been thinking it might be time to replace our old boiler, a Glow Worm Fuel Saver MKII from when the house was built in approx. 1988. after a short time surfing t'internet for info, i'm now confused as it seems new boilers may be more efficient, but they don't last more than 5 years?!

so, (without being too technical as i am a laydee ) our current boiler needs a service & the system flushed sometime soon.

a system flush is required as the 'valve' appears to be getting stuck & the motor/pump is suffering with vibration as it's having to work hard to get everything moving. this problem has happened before & the motor burned out & was replaced last January. the system wasn't flushed in Jan (but it was done within the last 4 years or so) & so we've got the same issue again now. (£300-£400 for service & flush?).

it's a heat only system with a tank, we've got a power shower so a combi boiler isn't an option. looking on Which?, the Glow Worm Ultracom hxi condensing boiler gets recommended (£800 approx.). with 'mates rates' for fitting i'm guessing this would be another £500-£650'ish on top.

but, various opinion seems to suggest that it would be best to stick with our trusted old boiler even though it's less efficient. any gas savings would take years to recoup & the new boilers need replacing a lot sooner.

help?! :|

(3 bed detached, double glazed, cavity wall & loft insulation. pay Npower £1200 per year for gas & electric. a third of our radiators have thermostatic valves).

 

[cjd]

This doesn't seem like a boiler issue to me at all. It sounds more like a design problem in your system. Changing the boiler will make no difference to how your pump and valves work of why your system is clogging up (if it is).

I would get a survey done of your system by a proper heating engineer - not a plumber or a mate (unless he's an engineer of course). This would normally be free from a reputable company as they hope to sell you the fix.

Be wary of system flushes, they are all the rage these days but you need to get to the cause of the problem before you hand over the cash - it may be that you have old and rusting radiators and no corrosion inhibitor in the system.

 

[*Lexxy*]

i agree it's not a boiler issue, but looking at what might be needed to fix the existing problem had made me consider if this would be a good time to change the boiler.

thanks for your advice

 

We have an oldish bosch combi.

we were advised by our corgi fitter that it was a much better quality than modern boilers,and that the cost of replacing any parts that may go wrong was minimal compared with having a replacement boiler.

His opinion was that any savings in efficency a new boiler may give would be lost many times over by the shorter lifespan of modern boilers.

He also offered the opinion that the boiler scrappage scheme was far more about increasing the sales of boilers,than any benefits to your average housholder.?

Earl

 

[markD1968]

I've got to agree it's not a boiler issue.

When I come across this sort of situation I would suggest a powerflush which when done correctly will clean the system throughly. Then have a magnaclean filter fitted. This will collect the sludge producing products before they cause a problem. Also make sure that you have inhibitor added to the system (do this every year as it doesn't last for ever). If your enginer feels that it appropriate then a product called Siltfree can be left in the system. This will have the effect of keeping any sludge that is formed mobile so that it doesn't settle out and cause a problem.
Hope this helps

 

[MASSEY]

Just go with the power flush, i would,nt get involved messing around with the boiler for more efficiency it will take years to get it back.

 

[Joseph H]

I would have to disagree with the life span of boilers being shorter, Many come with 5 years warrenty as standard, plus with the amount saved from how efficent they are it works out cheaper than replacing parts in your old boiler.

half the problem with peoples systems is that they never have there boiler nor system correctly serviced.

 

I would have to disagree with the life span of boilers being shorter, Many come with 5 years warrenty as standard, plus with the amount saved from how efficent they are it works out cheaper than replacing parts in your old boiler.

half the problem with peoples systems is that they never have there boiler nor system correctly serviced.

I disagree

cost to install new boiler seems to be £2,000

for that you can buy 4 new boilers.

My boiler is well over 10 years old total cost to date for maintenence £175.00

Parts are cheap as chips its the labour that costs.

Earl

 

[Stuart Walker]

i would look at fitting the magnaclean as this will reduce magnetic build up in the system, and by adding a good dose of a quality inhibitor you will more than lightly free up any items that are causing problems

the only thing i would check is that at least one of the radiators does not have a thermostatic valve as by having them on all the rads you stop the flow of water round the system when they are all satisfied and this could be causing the pump to throw a fit

questions to the engineer you have been using should be

1. when was inhibitor last added to the system(should be topped up every two years, one bottle normally good for ten rads)
2. is their a manual or automatic bypass on the circuit(needed to allow water to flow when all rads are satisfied)
3. are their cold spots in the rads(sign of blockage)
4. have you stripped and tested the head of the two/three port valve to make sure the springs are still their(the spring inside the valve switches off the power to the pump after a request for heat has stopped by releasing a microswitch)

might give a clue as to possible problem

 

[*Lexxy*]

thanks for all your input

some of it seems common sense, other bits are a bit 'whoosh' to me i'm afraid! but at least i'll have some useful info/questions for when our guy does come to have a look.

thanks again for taking the time to reply, i appreciate it (& this is why i 'love' the net, information & opinions at your fingertips!).

 

[Mpg]

Not relevant to latest topic but.

We have a Ultracom hxi crackin boiler esp when you add the thermastat

But i would have a bosch/ worcester boiler again. once out of warranty they do flat repairs costing £175

 

[profitxchange]

I agree with the themes of the contributions. I have a 20 yr old oil fired boiler - it works fine - serviced every 2 years. enquired about more efficient replacement - would only take effy from 85 to 95% - would take forever to recover cost. We moved into property 18 months ago. Have drained and cleaned system twice with inhibitor added and it works very well. still get a bit of air in system but that is due to biological action which I need to fix. Well worth taking a look at your multiposition valve motor - they do stiffen up and need a bit of a clean and lube to regain their full motion.

 

[Stuart Walker]

The cost of replacing the oil boilers is not as simple as just the efficiency, due to the boilers heating up quicker and running at higher temperatures you will save more than just the 10% efficiency as it will use less oil to heat the house in the first place

on top of this oil boilers are special as they can be tuned up and down to adjust the overall kW output, as most boilers that are currently installed were put in over twenty years ago before high fuel cost and energy efficiency were though about you normally end up putting in a smaller boiler than you currently have

if an engineer tells you they are just going to swap the boiler like for like without sizing the house, show them the door, by not checking they could be costing you thousands over the lifetime of the boiler

unless your boiler is knackered don't buy a new one, replace windows and doors, get cavity wall and loft insulation, upgrade to weather compensating controls, all of which will save you money

then once you have done all that you are in a position to replace the boiler, and if you can look at air or ground source heat pumps, they are more efficient, less harmful to the environment, and will not produce ever growing bills due to gas and oil companies raising their prices every five minutes

oil and gas are currently a commodity, but not for long, they will be a luxury in twenty years due to the fact they are running out

 

[Joseph H]

I disagree

cost to install new boiler seems to be £2,000

for that you can buy 4 new boilers.

My boiler is well over 10 years old total cost to date for maintenence £175.00

Parts are cheap as chips its the labour that costs.

Earl

That maybe so but how much extra are your paying in fuel bills a year? it all adds up

 

That maybe so but how much extra are your paying in fuel bills a year? it all adds up

Not a lot I would think if we look at how a boiler works.

In mine a gas flame heats water which is then circulated through the system.

Now the only way I know to heat water more efficiently is to use thinner metals between the gas flame and the water container.

Now its true you can probably play around with the design shapes of the components.

But it is always going to take x amount of gas ( or energy ).

to heat x amount of water.

sure someone will tell me thats wrong.

Earl

 

[G. Lasagne]

To say boiler parts are cheap, is only true on certain boilers some parts can cost over £600, then there's the cosmetic look of a new boiler as apposed to an old one, then there's the efficiency issue, you can easily save £350 going from an old back boiler to a band A condensing combi.

So i think every case is different, if you have a vailant or worcester band d boiler in a 2 bed flat then a band a combi isnt gonna save you much money.

But if you have a 5 bed detached with a back boiler then a band a would.

Like i say a new boiler can make both a big and small difference.

 

[G. Lasagne]

Not a lot I would think if we look at how a boiler works.

In mine a gas flame heats water which is then circulated through the system.

Now the only way I know to heat water more efficiently is to use thinner metals between the gas flame and the water container.

Now its true you can probably play around with the design shapes of the components.

But it is always going to take x amount of gas ( or energy ).

to heat x amount of water.

sure someone will tell me thats wrong.

Earl

I would stick to the seo earl.

Condensing boilers have larger heat ex changers, so that it takes less energy to heat the water, they also cool the combustion products to create energy (thus the condensing part) also they have modulating gas valves, secondary heat exchangers etc etc etc.

In brief they are designed for just that reason (to use less gas to provide the same amount of heat).

However a condensing boiler only condenses when the flue gases are cooled to 55 degrees, so for that to happen the flow , return pipes and radiators need to be at 55 degrees for the transfer to take place, however a normal flow,return and radiator system heats up at around 80 degrees so the condensing process only takes place when the boiler is first fired up, unless the installer has also installed high efficiency radiators and made other alterations.

So you are half right

But as far as using thinner metals, they need to be made of heat conductive material, i.e copper, you cant make it thinner as it would be more prone to corrossion and wouldnt conduct the heat properly, and therefore the thinner metal would actually cost you more money.

Thats what i remember anyway, im more a pencil pusher these days

 

[Joseph H]

Not a lot I would think if we look at how a boiler works.

In mine a gas flame heats water which is then circulated through the system.

Now the only way I know to heat water more efficiently is to use thinner metals between the gas flame and the water container.

Now its true you can probably play around with the design shapes of the components.

But it is always going to take x amount of gas ( or energy ).

to heat x amount of water.

sure someone will tell me thats wrong.

Earl

Newer boilers condensing boilers extract heat from exhaust gases which would uasaly just get sent out through the flue, which is a wate of energy.

Older non condesing boilers flue gases are around 180°C, with the newer condensing boilers the exhaust gases pass through additional heat exchanger and aid heating the water up, it then brings the temprature of the the flue gases dow to around 56°C.

which = better efficency

 

[Joseph H]

beat me to it G. Lasagne

 

[G. Lasagne]

56 , i said 55 so not bad i was only 1 out.

I think to close this thread, its fair to say that it all depends on what your current heating system and demands are, i often advise customers not to change a boiler if the currnet one is in good nik.

Plus i must admit that condensing boilers do not last as long as earls old worcester thats a statistical fact, but dont tell anyone

 

Newer boilers condensing boilers extract heat from exhaust gases which would uasaly just get sent out through the flue, which is a wate of energy.

Older non condesing boilers flue gases are around 180°C, with the newer condensing boilers the exhaust gases pass through additional heat exchanger and aid heating the water up, it then brings the temprature of the the flue gases dow to around 56°C.

which = better efficency

see I knew there would be a load of smart ases to tell me I was wrong.

so the exhaust gasses are reused to aid the heating process.

so where do they end up.?:|

Earl

 

[Joseph H]

see I knew there would be a load of smart ases to tell me I was wrong.

so the exhaust gasses are reused to aid the heating process.

so where do they end up.?:|

Earl

once as much heat as poss is taken out the gasses go out the flue as normal, this process does make a lot of condensation which requres a pipe coming out of the boiler then into a drain hence the name condesing boiler

 

[G. Lasagne]

see I knew there would be a load of smart ases to tell me I was wrong.

so the exhaust gasses are reused to aid the heating process.

so where do they end up.?:|

Earl

well when the fumes are cooled down by the process the fumes turn in to water vapour/condensation which is stored in the boiler before exiting the boiler via the condensate pipe, its "apparently" highly acidic, which is another reason why they dont last long

 

[Joseph H]

Dave you not painting a nice way for us to sell new boilers to the public haha

They may not last longer but the money saved on your fuel bills makes them worth while

 

well when the fumes are cooled down by the process the fumes turn in to water vapour/condensation which is stored in the boiler before exiting the boiler via the condensate pipe, its "apparently" highly acidic, which is another reason why they dont last long

sounds sensible to me.

can't they use materials not affected by acids.?:|

Earl