Boiler help, please! Change to a Combi?

[Gozogozo]

4 of us in a mid terrace with a 7 year old condensing boiler (Icos 24HE) that works fine in a 3 story house with 2 pumped power showers (1st & 2nd floor) & 3 loos. Also a 7 year old hot water cylinder & immersion switch.

We have 18 litres per minute flow from the kitchen tap & are in the middle of building an extension so the boiler will have to be moved as the back wall to which it is attached is moving.

Our builder & his plumber want us to change to a worcester combi (37?) & move to the 2nd floor from the ground floor, which they reckon will give us the pressure that I need (v bad back which seizes up every night & hot strong shower eases stiffness), removing the need for our pumps, losing the hot water cylinder, so gaining that space. We are also having a water meter fitted with a 32mm pipe from pavement into our house. The old pipes are approx 15mm lead pipes.

We have ruled out the full upgrade to mains pipes from the road to house as approx £3k, plus the cost of a megaflo or similar.

My worries are:
the pressure from the shower not being as good as now
Combi boilers possibly more likely to develop problems due to their complexity
Is there any problem with having the boiler on the top floor rather than the ground floor?
Loss of our immersion heating facility which has been a godsend when we have 12 or more people to get through showers eg at Xmas, or in case of boiler problems.

Has anyone else been through the same dilemma and if so, what did you choose?

TIA

All I know is that shower pressure being better is meant to be one of the significant benefits of a combi, but also, that a combi is best when you only use one shower or bath or even hot tap at a time.

So I would look into these questions. Sorry not to be more help.

I would actually definitely stick with a system boiler reading your last concern.

I have a combi boiler. The pressure from the shower is superb - better than my parents' power shower. I don't know how much of this is due to the boiler itself though. However, you can't really run more than one tap at a time. This has never been a problem for us though.

Loss of our immersion heating facility which has been a godsend when we have 12 or more people to get through showers eg at Xmas,

A combi boiler heats water on demand though so you never run out. I filled my birthing pool with hot water using mine :) Of course, in the case of boiler failure this isn't going to help but we do have a rubbish electric shower downstairs to use in that eventuality. It's happened before when the old combi boiler reached the end of its natural life.

No that's true actually. You shouldn't run out. Technically. Just depends how many people are using hot water at the same time.

We have a combi boiler (Worcester Bosch, greenstar 42cdi) and never had any pressure problems. Actually I use the hot shower on my aching back every day, def enough pressure.

I have no idea how thick any pipes are, the whole house was replumbed but the connection from house to street is still the old one.

Our boiler is on the ground floor and showers are on first and second floor.

When another tap is on (or the washing machine) I feel the difference in flow rate temporarily, but it is still plenty!
Our plumber commented on the fact the boiler is over the top, but the difference in flow rate was only £150 and I wanted to make sure. In our old house the shower was reduced to a dripping tap whenever another tap was on, we all hated it.

I am not a combi enthusiast.

Why don't you like the cylinder and pumps?

You mention a new 32mm pipe, and some lead pipes. Where are the lead pipes?

Thank you all, your posts have been very helpful.

I have since rung Worcester Bosch, who are amazingly helpful as well, and they confirmed that I should get another heating engineer to double check, but for all the worries that I mentioned in the OP, a system boiler would probably be best, and boiler located on the same floor as the cylinder ideal. He also pointed out that getting a twin coil rather than a single coil cylinder would make sense if we were thinking about using solar energy at any point.

So, onwards!

if you can afford a Megaflo now, you might consider putting one in, with the potential to upgrade the water supply pipes later.

Depending on how much of your piping is old, and how much is new and large, it's possible you will already have enough flow. Lead pipes can last 100 years, but tend to constrict flow if they are underground as they can get squashed.

Sorry PJ, cross post! Was hoping that you might pop in

I have no problem with the cylinder. It means that I have a lovely airing/linen cupboard. We don't desperately need that space for anything else.

The set up is that we have the original 15mm lead pipes from the water main into our house, to the kitchen sink, and flow is 18 litre per min.

We were considering a megaflo, no idea why really, just that everyone kept telling me that they were the dogs wotsits for great shower pressure. Thames Water came out & told us that to change the pipes to 32mm MDPE would cost £3k to dig up road (7m distance) & upgrade cold mains to the stopcock outside our front garden & a further £500 to upgrade the pipe from that stopcock to our indoor stopcock, under the stairs, with our builder digging the trench etc. So we forgot about megaflo, as with the cost of that cylinder, plus the install costs, plus new boiler, plus removing shower pumps from 2 showers, it was all spiralling into excessive costs.

Our builder's team is clearly very experienced at installing combis & has been doing so for over a decade, has one himself and I worried that he wasn't entirely listening to my concerns. So I went into research overload on diynot 7 here & phoning WB & Vaillant.

Crossposted again!

If I revisited megaflo or similar, can i get a twin coil one to work off solar?

And presumably if I have an unvented pressurised cylinder, i could have an immersion in case of emergency?

(I'm keeping a gas fire in the living room as again it proved very helpful when the boiler stopped during the very harsh winter recently. Risk averse, that's me.)

Our heating engineer is an ex neighbour and fitted a new system for us, he specifically refused to fit a combi-boiler for us for the reasons you are worried about, as a new tank system it's really efficient compared to the 25+year old boiler it replaced & we've never run out of hot water in the 2 years we've had it. Had a combi-boiler and boiler fed shower in our last house, it was a pain in the neck as you had to turn the shower up high to get the boiler to kick in and start heating water, then if you turned the temperature down too much the boiler would go off again

Oh, and it shouldn't matter about where it is, as long as you can vent it properly, we considered the attic but then went for the cellar as we are more likely to develop the attic in later years and didn't want to have to move the boiler.

you can have two immersion heaters in a Megaflo if you want, one near the top for small amounts quickly, and one near the bottom for large amounts slowly. If you were to get solar PV (electric) roof panels it is a good way to use your free electricity.

Have you got a water meter? The pipework inside the boundary of your home and garden belongs to you, and you can dig a trench and lay new pipes yourself. If there is a water meter in the pavement, it incorporates a stopcock, and new pipe can be connected to it quite easily (though it usually involves digging up the pavement, I have known a plumber say he could burrow in from the garden, but this might not be "allowed"). If there is not yet a water meter, but you lay a new pipe all the way to the pavement, the fitters should be willing to connect it to a meter if/when one is fitted.

If the pipes belonging to the water co are lead, then sooner or later they will replace them. They may also have a Lead Pipe Replacement subsidy, and if you replace your own lead pipes, they may have a policy of replacing theirs at the same time. Contact the water co and ask them to test your drinking water for lead content. This will be key to getting any grant or subsidy, and may pressure them. Policies vary by local water co. There is no charge for the lead test, but it must be done before you start work.

Finally, old lead pipe can be replaced with new plastic. Even if there is still a short piece of narrow old pipe at the pavement, you will find the flow improves noticeably if you replace a long section in your property. I would be inclined to leave an access hole to make it easier to connect your new pipe when the old water co pipe gets replaced (as one day it will)

PigletJohn,

Your second para about replacing the lead pipe from just inside boundary into house is the one that our builder plans to do. I did request a lead in water test but they failed to do it before we started other building works so now seems unlikely that they will, as they require to test with no works happening in last 6 weeks & connected kitchen sink & tap (well, we still have that, but the rest of the kitchen has been ripped out already)
So I don't think that they will replace the lead pipes to the main under the road anytime soon.

We are getting a water meter fitted to the stopcock literally next to our boundary wall. The somewhat jobsworth individual turned up an hour early for his 1-5pm slot & said that all he was tasked to do was spray the stopcock blue for the benefit of other Thames water colleagues who would insert a 32mm fitting water meter sometime in the next 30 days (but that he wasn't insured to spray it blue till 1-5pm??? so hung around for an hour...) Meter can be removed in next 12 months if more costly to us.

The builder then plans to dig the trench & fit 32mm mdpe to the stopcock & boiler (I think) & 22mm copper pipes to showers where not already 22mm. So circumventing the extra £500 for connection, but still incurring the labour cost of trench...

Re the lead test, I complained on the phone to Thames Water that they hadn't done it nearly a month after requesting it, and work is now clearly underway...do I stand any hope of getting the test done, do you think?

Oh, and the access hole - presumably I can't just leave an uncovered hole in the ground? What should I ask the builder to do?

Thank you so much! NN should really be Plumbing HeroJohn.

We had our mains replaced and the waterboard did the connection for free. We had to dig the trench and lay the pipe, but they did the connection gratis.

put a manhole cover over it.

You may be able to get a plastic pit segments of a convenient size, I am more used to concrete or brick, which are stronger if you intend to drive vehicles over it. If the pit is not lined the sides will tend to collapse inward. A thick ply box would last for a few months.

I would be very keen on having at least a short piece of new plastic pipe put ready to connect to the meter. It can have a stopcock put on it to ease connection to your new length when ready. Otherwise the metermen might connect your old lead pipe to the meter. You really want a new plastic stub that crosses your boundary, to save having to dig up the pavement again.

As for the slow appointment for lead test, that is depressingly common, and it's probably too late now. You may as well have it done anyway, as it's free.

Thank you.

Re plastic stub, he plans to do that. I assumed that he would remove the old lead pipe that is within our boundary so that all Thames Water would have to fit to the meter was our 32 mm pipe? Is builder supposed to leave old lead pipe lying in trench unconnected to anything or am I missing something? (I misunderstand easily as it's my first & hopefully last ever building project!)

Also, if we had the Megaflo or similar installed now, our shower pumps would need removing. There's no guarantee that the pressure to showers would match the previously pumped pressure is there? Even with 32 mm pipes to the pavement & Worcester 42cdi system boiler?

there will be a bit of old pipe connected to the watermain in the pavement, that will have to stay there until the meter is fitted. The new stub will have to be in place, long enough to reach the meter, but not connected. After the new stub has been connected to the meter, it can be connected to (the rest of) your new pipe. This could be done in a stopcock pit just inside your boundary, there probably is one, or was when the house was built but has since been paved over or filled in. A larger house may have a brick-lined pit, but a less expensively built house might just have an arm-sized hole.

Once old lead pipe has been disconnected at each end, it can be taken up and sold as scrap. The route of the new pipe need not be the same as the route of the old pipe, so may not be worth digging up.

You can keep the shower pumps as long as your baths are supplied from a cold water storage tank in the loft. A megaflo is just a special sort of cylinder, you can supply it from a cold loft tank if you want. Once that goes, you will have to stop using the pumps. Apart from some special exceptions, you are not allowed to use pumps to suck from the watermain.