Central Heating Boilers:

[MrMessy]

My daughter needs a new gas combi boiler in her flat in London. Are they any particular makes to avoid? One plumber recommended an Instagas Boiler. I have never seen these advertised in the Trade mags. but Plumbase sell them. He said they are really well built and reliable? Are Biasi any good? Any help with this would be gratefully appreciated.

[Seeker]

I was recommended to get a Worcester (owned by Bosch) and they seem to get good reviews. 5 years old and, touch wood, no problems.

[SV650rules]

Worcester Bosch are a good boiler and made in UK ( In Worcester of all places !). Vaillant make good boilers but charge like a wounded bull for them ( and read experiences below).

The older cast iron boilers were not so efficient as modern condensing boilers but they used to last centuries without problems. Modern boilers are only designed for a service life of 6 to 7 years. I read an article once to tell people not to go for a new boiler under the government scheme if they had a good old boiler that was still working because it did not make economic sense to trade in a boiler that would last forever and was 85% efficient for a new boiler that was 90% efficient and that will be 2 grand thank you and will only last less than 10 years. We have a Vaillant condensing boiler (the dogs dangly bits of boilers and priced to suit) fitted to our house when we moved in 20 years ago, still working but it is a bit like triggers broom, 3 new fans ( £180 a time ), 2 new pressure switches ( £90 a time ), one new water pump (£200), one new main printed circuit control board ( £300) and a new heat exchanger ( £400 ). The problems with the fans was mainly caused by the original installer sloping the horizontal balanced flue pipe back towards the boiler instead of away from it - this meant that condensate from the flue drained back into boiler onto the hot heat exchanger casing, flashed into steam and turned the normally dry area where the fan sits into the equivalent of a steam room, this corroded the (unsealed) fan bearings and the PCB (despite ACF-50 and WD-40 on the board and connectors). You can buy bearings from Cromwell or RS for a few quid but have to destroy the fan to get to bearings as plastic fan impeller is glued on and the rotor of the variable speed motor is welded on to the other end of shaft).

In our older house we had a Potterton back boiler that was fitted before WW2 and still working fine 50 years on.

No matter how 'efficient' an expensive new condensing boiler is compared to an older one it will take longer than the new boiler is gonna last to get your money back, then you have to get another new one, and prepare for some hefty repair bills on you new flimsy model.

[shiftin_gear98]

I'm on my second Vaillant boiler. To be fair I did move house.
Both properties had a prehistoric boiler when we moved in. The house we are in now had one that was part of the worktop in the kitchen. WTF. It was practically condemned on our survey.


Anyhow I digress.
First house we were there nearly 5 years. No issues whatsoever.
Second house been there just over 3 years. No issues whatsoever.


Had one of these fitted in both. Vaillant ecoTEC Plus 835 Combi Boiler.

[Bibio]

baxi back boiler installed some time in the 80's, serviced once a year and had only one water pump replacement and one thermostat. i'm looking to get a combi installed but only for the space saving. otherwise i'm happy with the baxi.

my father was a plumber and always said to get a Worcester combi as the flow rates were better than the cheeper ones.

if you have a household that is continually using hot water then it might be best to get a proper boiler and hot water tank otherwise your combi will always be switching on/off which causes quicker failure. same goes if your central heating is on all the time then with a back boiler you always have hot water rather than making the combi work twice as hard.

personally its the space saving that i want as the hot water tank takes up a large corner of my kitchen.

[Sir Trev]

Beware of plumbers who condemn old cast iron boilers. They may well be after your money to replace then with a shiny new one out of greed or laziness. Happened to us - elderly Potterton floor-standing job in the house when we moved in, we played Russian Roulette with Yellow Pages after finding the kitchen full of carbon monoxide one morning and the guy took one look and said it had to be condemned* as it was unserviceable. Had a second opinion (thankfully) and this guy rolled up his sleeves and got filthy vacuuming out all of the soot that had built up. Once done it was fine!

When we remodelled the house we did replace the boiler but only because the output was not up to the new layout. Shame. The new Potterton we have now has had new fans, PCBs, heat exchangers, etc. too because the builders installed it wrong. Now fixed and, touch wood, it's been fine for over five years with minimal annual servicing costs. It's eleven years old now so I dare say it may be on borrowed time...


*oddly, despite being Corgi registered (it was a few years ago) the idiot that condemned the old boiler did not actually condemn it. He left it going... Something the second opinion guy was disgusted at and said he would complain about. However, the same a-hole did some shoddy work for my neighbour a few years later (I recognised the van) as a subbie on their extension. They were not happy either.

[SV650rules]

Combi boiler pretty much twice as complicated as a normal boiler. Has separate heat exchangers for CH and HW with the added problem of the pressure switch that is supposed to sense when a tap or shower is turned on and fire up the burner, but can be very temperamental. Combi also only good with smaller properties with only a few possible hot water outlets. I replaced our 20 year old pressurised Vaillant mild steel glass lined hot water tank last year with a Sadia- Heatrae stainless tank. Got fed up of replacing the sacrificial anode at £50 a pop, and worrying when tank was going to corrode and flood the house. Had a glass lined mild steel tank fail in one house and it made an awful mess, never trusted them since. Mind you the tank failed in a soft water ( acidic) area, hard water is much less corrosive, even copper pipes do not survive as long as they should in soft water and develop pin-holes - not good news. Good news is that we now live in hard water area.

[Bibio]

hard and soft water is not dictated by the acidity of it but both often go together. soft water has less salts than hard water.

for domestic tap water to corrode copper piping the acidity would have to be constantly under a pH of 2 which you would notice straight away if you drink it.

living in a hard water area is bad as it has a higher content of salts which build up in pipework etc.etc. soft water areas have no such problem.

[timwilky]

We have a Worcester,at two years old. The plastic pipes were dripping, service tech tried to tighten them and the joint disintegrated. A few years later it starts to act up. Because the control board had water damage we could not get British gas who then had the contract to replace the board. the boiler worked but when hot water on would keep switching off the burners until the hot water ran cold and then turn them back on. The only way to fill the tub was to turn the tap 30% open.


Different fault and the young British gas tech had a water disaster and blew the control board. Yippee in goes a new one and the fault fixed.


Worcester boilers.....Supposed to be good, Ours must have been a friday job. Leaky pipework. 3 diverter valves in 10 years, Even though the control board is fixed and the burners stay on. It cannot heat the hot water for the tub at full flow.

[SV650rules]

hard and soft water is not dictated by the acidity of it but both often go together. soft water has less salts than hard water.

for domestic tap water to corrode copper piping the acidity would have to be constantly under a pH of 2 which you would notice straight away if you drink it.

living in a hard water area is bad as it has a higher content of salts which build up in pipework etc.etc. soft water areas have no such problem.

The generally accepted definition of hard water is water containing dissolved calcium from limestone areas. Soft water is pure water with fewer dissolved solids.

Water with ph less than 6.5 can cause corrosion, hard water coats the inside of the pipes (that is the bad news) the good news is that the calcium coating prevents corrosion of the pipes. acidic water ph<7 continually tries to remove the protective oxide coating from metal pipes, hard water covers the oxide coating with a protective layer. Lead pipes in water supplies were not really a problem in hard water areas because inside of pipe was protected by limescale, in soft water areas though they water dissolved the lead and people were drinking it. My brother used to work for a water purification company who supplied treatment equipment to water suppliers like Severn Trent, Yorkshire water etc. They preferred Hard water to soft as it was easier on their equipment as it reduced corrosion problems. If your boiler or heating system has any aluminium in it you should not use soft water, if you have a water softener fitted to your house you should take off the water for heating system ( filling loop ) before the softener. The anti-corrosion heating system additives like Fernox raise the ph of water to protect pipework and boilers.

http://www.kamco.co.uk/GuidanceNotes/PDF/Watertestkitinstructions.pdf

https://www.combimate.co.uk/sof****er-corrosion.html

(https://www.combimate.co.uk/sof****er-corrosion.html)
https://www.water-research.net/index.php/drinking-water-issues-corrosive-water-lead-copper-aluminum-zinc-and-more

(https://www.water-research.net/index.php/drinking-water-issues-corrosive-water-lead-copper-aluminum-zinc-and-more)

(https://www.water-research.net/index.php/drinking-water-issues-corrosive-water-lead-copper-aluminum-zinc-and-more)

[Red ones]

hard and soft water is not dictated by the acidity of it but both often go together. soft water has less salts than hard water.

for domestic tap water to corrode copper piping the acidity would have to be constantly under a pH of 2 which you would notice straight away if you drink it.

living in a hard water area is bad as it has a higher content of salts which build up in pipework etc.etc. soft water areas have no such problem.



Not true.

The salts in hard water act as a buffer and raise the pH without them the pH drops below 7.
Copper will suffer pitting at even pH6 which then creates corrosive sulphates. (These cause the blue lining you see inside pipework when you cut it)


I have a smile of the day now. A degree in Chemistry, teacher training in science, and 20 years in a career which involves water chemistry and at last I use my knowledge!!!

[Bibio]

Not true.

The salts in hard water act as a buffer and raise the pH without them the pH drops below 7.
Copper will suffer pitting at even pH6 which then creates corrosive sulphates. (These cause the blue lining you see inside pipework when you cut it)


I have a smile of the day now. A degree in Chemistry, teacher training in science, and 20 years in a career which involves water chemistry and at last I use my knowledge!!!

glad to be of service ;)

riddle me this then... i have soft water but the pH is 8-8.5

[Red ones]

Why do you say it's soft?

[Bibio]

Glenfarg is my water supply which is moderately soft hardness level. besides that if the dissolved solids were correcting the pH to 8-8.5 then i would not get much of a lather when using soap like other hard water areas, but like almost everywhere else in Scotland its well bubbly lather.. there are very very few hard water areas in Scotland.

i know the reason why, but i'll let you work it out. i'll give you a hint though.. this has only happened within the past 10 years which before that it was pretty much bang on a pH of 7

i have never to date heard of anybody having rotted/pinned copper pipes in Scotland due to the water pH.

[maviczap]

I'm on my second Vaillant boiler. To be fair I did move house.
Both properties had a prehistoric boiler when we moved in. The house we are in now had one that was part of the worktop in the kitchen. WTF. It was practically condemned on our survey.


Anyhow I digress.
First house we were there nearly 5 years. No issues whatsoever.
Second house been there just over 3 years. No issues whatsoever.


Had one of these fitted in both. Vaillant ecoTEC Plus 835 Combi Boiler.

Another Vaillant owner here, had ours for nearly 17 years now. Early on we had problems, but after the ignition board was changed, touch wood it's been trouble free.

My only gripe is that it only supplies enough hot water for one shower, if some turns a tap on or flushes a look, then the shower goes cold. Not a big problem, just irritating.

My mum also had one, so plumbers must think they are ok?

I did prefer the system I had in my previous house, which was a normal boiler and a mini tank, which held enough hot water to fill a bath. If I have a new boiler fitted, I might go back to having a mini tank and have it heated by a boiler or solar panels.

[SV650rules]

Glenfarg is my water supply which is moderately soft hardness level. besides that if the dissolved solids were correcting the pH to 8-8.5 then i would not get much of a lather when using soap like other hard water areas, but like almost everywhere else in Scotland its well bubbly lather.. there are very very few hard water areas in Scotland.

i know the reason why, but i'll let you work it out. i'll give you a hint though.. this has only happened within the past 10 years which before that it was pretty much bang on a pH of 7

i have never to date heard of anybody having rotted/pinned copper pipes in Scotland due to the water pH.

Here is a engineering bulletin from Scottish NHS - you only have to go as far as section 1 to see warnings of effect of soft water in Scottish Hospitals on copper piping, they recommend stainless or plastic piping is used where possible. More bad news from the paper is that epidemiological studies have found higher incidence of cardio vascular disease is higher in soft water areas than hard (this is further down in the paper).

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=2ahUKEwjb-eGdoezdAhXhLsAKHZ9yCDkQFjABegQICRAC&url=http%3A%2F%2Fwww.hfs.scot.nhs.uk%2Fpublication s%2F1475663182-SHTM%252004-01%2520V1%2520Part%2520E.pdf&usg=AOvVaw1womlXS-fVjHpf_by8_q-l

[Heorot]

I grew up in Northamptonshire and moved to Norfolk, both hard water areas. The first shower I took after moving to Edinburgh I used the same amount of shampoo as in Norfolk and then spent ages trying to get the foam out of my hair. The water came from a reservoir in the Pentland hills.

[Bibio]

Here is a engineering bulletin from Scottish NHS - you only have to go as far as section 1 to see warnings of effect of soft water in Scottish Hospitals on copper piping, they recommend stainless or plastic piping is used where possible. More bad news from the paper is that epidemiological studies have found higher incidence of cardio vascular disease is higher in soft water areas than hard (this is further down in the paper).

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=2ahUKEwjb-eGdoezdAhXhLsAKHZ9yCDkQFjABegQICRAC&url=http%3A%2F%2Fwww.hfs.scot.nhs.uk%2Fpublication s%2F1475663182-SHTM%252004-01%2520V1%2520Part%2520E.pdf&usg=AOvVaw1womlXS-fVjHpf_by8_q-l

" SHTN 2 addressed the problems experienced by the NHS in Scotland in
consequence of the corrosion of copper pipework systems. Despite extensive
research, the absolute cause of the corrosion has never been precisely
determined, but enough was understood to conclude that copper pipework in
Domestic Hot and Cold Water (DHCW) services in hospitals and other healthcare
premises in many areas of Scotland (and elsewhere), with soft water, and / or
where high levels of sediment were found, had a high propensity to failure. "

says it all really.

its all just someone getting paid huge amounts to talk pishz and justify their job and get work through the door for their mates.

my father was a plumber/heating engineer all his working life in Edinburgh and Fife. if there was pitting on copper piping due to soft water then he would have mentioned it. i know a fair few people in the trades and not one of them has ever mentioned rotting copper piping.

[Talking Heads]

Worcester Bosch use a lot of Italian made parts.
Every part I've ever had replaced in a Worcester boiler (one gas, two oil) was made in Italy.

[Bibio]

yup, pretty much all your white goods are made in Italy or Spain.. hello massive price hike after brexit....

[Ruffy]

Well, based on my previous personal experience, if I were in the market I'd probably be looking at Worcester Bosch first. However, some of the others' experience listed here makes me pause for thought and I would look more widely.


Also, I would be looking at some sort of way to tie in solar capablity too (probably traditional boiler and a heat store water tank, rather than combi), but that may not be practical for the London flat that the OP is considering.

[Littlepeahead]

Which? Magazine reviewed boilers this month.

If you pm me your address or email I'll send you the article.

Sent from my SM-G935F using Tapatalk

[Red ones]

Glenfarg is my water supply which is moderately soft hardness level. besides that if the dissolved solids were correcting the pH to 8-8.5 then i would not get much of a lather when using soap like other hard water areas, but like almost everywhere else in Scotland its well bubbly lather.. there are very very few hard water areas in Scotland.

i know the reason why, but i'll let you work it out. i'll give you a hint though.. this has only happened within the past 10 years which before that it was pretty much bang on a pH of 7

i have never to date heard of anybody having rotted/pinned copper pipes in Scotland due to the water pH.



Scottish Water have to correct the pH in a lot of areas. Legislation requires supplies to be between pH 6.5 - 9.5 in part to prevent corrosion, in part because below that range it tastes. (It also tastes above the range)

So long as the supply is regulated within the range the expected lifespan of copper pipework is around 45 years. Typically people won't re pipe a whole house unless they are remodeling but they are more likely to fix a leaking joint or replace a single length of pipe at a time.


Sent from my iPhone using Tapatalk

[SV650rules]

Water that is below 6.5 will leech out metals from piping mainly copper, lead , iron and dissolve it in the water, in really low ph areas this can cause 'blue water' if the dissolved metal is copper actually colouring the water and it will taste awful. As I said earlier my brother worked as a designer for a water treatment equipment manufacturer and they hated soft water as it corroded their equipment and they had to balance it before putting it into public network. It is not for nothing that distilled or de-ionised water is called 'the universal solvent'. The jury is still out if water softeners in your house cause corrosion, the manufacturers obviously say not, but in any case they do add sodium to the water which is not really ideal for drinking.

[Bibio]

it all doesn't help the OP about boilers but its an interesting subject.. well to me anyhoo.

can we agree that distilled water or indeed pure H2O has a pH of 7?

can we agree that any water no matter its pH or "minerals/salts" content can be adjusted using either phosphoric acid to lower or potassium hydroxide to raise the pH?

[Red ones]

To return to topic. I like Worcester Bosch.
Reliable, easy to get hold of parts of needed and well understood by engineers.

I had to get a new boiler a few years ago to replace a 30yr+ one. Went for a Greenstar and went from 60% efficient to 91%
Budget for it to last 10 years, after that consider it borrowed time. Get boiler insurance from year 2 but make sure that includes annual service and inspection - costs the same as just the service but your covered, usually for controls and leaks too.

I love the comments about old ones are best. Same used to be said of cars, but I don't see many people choosing to drive a Cortina.

[SV650rules]

Nothing to do with pH but I lived in San Antonio TX for a year, it gets its water from the Edwards Aquifer which is a vast underground limestone cave system https://www.edwardsaquifer.net/

In the US water hardness is defined in grains (of Calcium carbonate) per gallon. Very hard water has a range greater than 10.57, in San Antonio it varied between 15-20 gpg; a water softener was essential. We ended up buying an ion exchange softener (salt exchange) which swaps the Ca for Na. It worked very well but when we returned to CA we discovered they were banned (another $3000 blown). CA sells partially treated water for landscape irrigation and they could not deal with vast quantities of salt water that the softener dumped.

If you do have a water softener fitted it is recommended that it is fitted close to the incoming stopcock and 'after the drinking water tap' WTF - does that mean that you can only have one tap in the house that you can drink out of, or have separate piped drinking taps, clearly labelled. Softened water is not good for drinking because of the problem with sodium in the water (that has been exchanged for calcium) - calcium is much better for you. Water softeners are fitted mainly for washing machines, to save on detergent, so why not fit it next to the washing machine.

I would rather descale the kettle, washing machine and shower a few times a year than have my household plumbing quietly corroding away from the inside.

[SV650rules]

If you run the boiler temp too high on condensing boilers you lose quite a lot of the extra efficiency over 'a dumb cast iron boiler' because the heat exchanger is too hot to condense the flue gasses and extract the escaping heat before it goes out of the flue and into the wide blue yonder. Experts reckon boiler temp needs to be kept as low as possible for best condensing ( even below 40 deg C for room heating only), but you need to heat water in you combi or indirect hot water tank to at least 60degC. This paper reckons that the hot water side of a combi boiler does not usually get into condensing mode, so take 20% off that 91% that maker quoted in their blurb. You should see a definite white plume of water vapour coming out of flue, if you cannot see the plume as soon as the gases leaves your boiler is probably not condensing. We run our system boiler at boiler at 70 deg C flow temp ( we have 14 radiators so return temp is probably below 50 deg C, but I will check), I would run it cooler if it was only feeding radiators but it is also heating our hot water tank as well, and if your hot water storage is at too low a temperature it is a perfect breeding ground for bugs.

One fairly modern innovation for central heating is a thermostat mounted ouside the house which senses the out side temperature and adjusts the boiler flow temp (higher temp on colder days) - but the trouble is if the boiler temp gets too high we do not get the recovery of latent heat of evaporation from moisture in flue gases. Also if you have a lot of radiators with TRV on them to shut off flow at a certain room temp, as more radiators get shut off the temperature of return water to boiler rises and may take it out of condensing mode (even if it was in it to start with).


http://www.yougen.co.uk/blog-entry/1946/Is+your+condensing+boiler+actually+condensing'3F/

https://www.thisismoney.co.uk/money/bills/article-1710224/Are-condensing-boilers-a-waste-of-money.html

http://www.complianceforlandlords.com/advice/how-to-check-water-temperatures-to-control-legionella-risk/


Condensate from condensing boilers is extremely acidic and corrosive. this Australian article seems to suggest that draining it back into sewage / grey water system without raising the ph to at least 5 may be made illegal in Aus soon. Maybe this is why condensing boilers do not last long, they rot away from the inside.. I had to replace the condensate sump (aluminium, which is normally pretty good with acid) on our Vaillant, as I said it is like triggers broom. Found out something from the Australian article, just like the decibel scale the ph scale is a log scale, a ph of 6 is 10x more acidic than a ph of 7, so a ph of 2 ( condensate from natural gas boiler) is only one step up from battery acid,

https://www.automaticheating.com.au/solutions/condensing-boilers-explained/managing-condensate-condensing-boilers/

[Kenzie]

We are having a new combi boiler and new rads put in next week. We have just bought our first house (built 1961) and it has a hot water tank in the cupboard and a standard boiler in the corner of the kitchen. The rads are mismatched and don't have valves so will be changed and a couple relocated. The boiler according to the quote is a Baxi. So fingers crossed it is a good one. Might as well get it done now before getting stuck in with decorating.