Will I regret getting a combi?

ThisIsWeird

kittennose said:

Thanks very helpful.
Our shower is 3L/min and bathtub is 6L/min. It's appalling. Kids refuse to shower becasue it's just not nice. The top of the shower head to the bottom of the water tanks is about 0.5m. I can't see room to move these up significantly and we've been told a pump would be difficult for our setup.
 did consider digital showers, but these are £1k a piece.
The motivation for a combi was because If we had 10L/min shower this would be huge. I was hoping a combi would do that and along with the storage increase it would easily justify the extra £500 being quoted.
Our shower is right above the combi, so I was hoping this would help but to be honest I have no idea how they would plumb a combi in, whether it needs new pipes or not etc.
That was the temptation with a combi.
Keeping what we have is an option but clearly a harder one as we spend £3,500 and gain nothing in return other than maybe 20% off our gas bills.
Our Annual gas usage is 20,000Kwh - and we are very tight with the heating (max 18 and only boost for 1-2 hours per night in the week). so actually I expect better than 20% savings.
PS: We did get quite for a pumped accumulator, that was just under £5k alone.
As for heatpumps, we can get one for the same price as a combi, plus all new rads but unfortunately we have 8mm microbore and this counts us out as the whole lot would need repiping apparently.

Ok, that's all useful info.

Your shower is 3lpm?! Forgive me while I have a laff...

Cough - sorry.

That is clearly hellish, so - yes - a combi would be better.

Your 0.5m 'head' will be the reason for this. If there's no way to raise the height of the CWS, then almost certainly pumps can be used, but obviously I don't know why your plumber reckons this will be tricky.

Another solution is a shower with a built-in pump - I have seen these, and they really work well. https://www.amazon.co.uk/Triton-Showers-Silent-Running-Shower/dp/B0851BMG9L?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=A3P5ROKL5A1OLE

A combi will/should be able to use the existing water pipes, but will very possibly require a new gas supply to be run to it.

An accumulator is the ideal solution, whatever system you go for. £5k seems high for that - where would it go? Challis make nice units, and they are (used to be) around £1k or just above? It depends, of course, how hard it would be to plumb in.

"Keeping what we have is an option but clearly a harder one as we spend £3,500 and gain nothing in return other than maybe 20% off our gas bills." What would cost £3.5k in this scenario?

kittennose

ThisIsWeird said:

"Keeping what we have is an option but clearly a harder one as we spend £3,500 and gain nothing in return other than maybe 20% off our gas bills." What would cost £3.5k in this scenario?

A regular boiler replacement + clean and a new central heating pump.

ThisIsWeird

kittennose said:

ThisIsWeird said:

"Keeping what we have is an option but clearly a harder one as we spend £3,500 and gain nothing in return other than maybe 20% off our gas bills." What would cost £3.5k in this scenario?

A regular boiler replacement + clean and a new central heating pump.

Thanks. I was afraid of that. 
Who the heck is charging £3.5k for a replacement heat-only boiler?
Is there anything unusual in this installation? In the middle of the house, so tortuous flue route?
A friend had a new H-O boiler fitted, ok, two years ago, which necessitated a condensate pipe route. £1.7k.
I, perhaps, wouldn't grumble at even £2.5k IF it included a FULL power-flush, but £3.5?! Why?
Who quoted for this, and who else has quoted?

kittennose

ThisIsWeird said:

kittennose said:

ThisIsWeird said:

"Keeping what we have is an option but clearly a harder one as we spend £3,500 and gain nothing in return other than maybe 20% off our gas bills." What would cost £3.5k in this scenario?

A regular boiler replacement + clean and a new central heating pump.

Thanks. I was afraid of that. 
Who the heck is charging £3.5k for a replacement heat-only boiler?
Is there anything unusual in this installation? In the middle of the house, so tortuous flue route?
A friend had a new H-O boiler fitted, ok, two years ago, which necessitated a condensate pipe route. £1.7k.
I, perhaps, wouldn't grumble at even £2.5k IF it included a FULL power-flush, but £3.5?! Why?
Who quoted for this, and who else has quoted?

To be fair that's the cheapest we've got. I think it was heatable or BOXT. Roughly £2800 boiler, plus a new pump which we'd need (existing one is very noisy) a new valve plus a good magnaclean flush. 

Local outfits are all £4-5k and British Gas wanted £6500.

Not many locals want to do a standard boiler, either 40KW combi or system boiler and unvented.

ThisIsWeird

Which model boilers are we talking about? 
But, the companies you have mentioned do tend to be reasonable. 
There must be something a bit more involved with your setup? Any idea?

kittennose

ThisIsWeird said:

Which model boilers are we talking about? 
But, the companies you have mentioned do tend to be reasonable. 
There must be something a bit more involved with your setup? Any idea?

No, bog standard. Boiler in the same place, right up against where the flue is too so a very simple job I have been told.

Think it depends where you live too - if I put Manchester postcode in heatable it's 200-300 quid cheaper!

Boxt are a bit lower as they offer a 24/25kw boiler

ThisIsWeird

Blimey.
BOXT are usually well priced, so these quotes are a surprise.
These are big boilers for H-Os! But, even then, they are only around £1.4k to buy.
I'd be inclined to also ask a couple of local GSs too, getting them personally recommended if you can.
The more info and opinions you get, the better.
Hopefully you have a better idea of the options available to you, although it's pretty clear you have a good handle on the issue.
Please keep us posted. Let us know of any developments, and any more info.

FreeBear

kittennose said: Not many locals want to do a standard boiler, either 40KW combi or system boiler and unvented.

With a flow rate of just under 12l/min, a 40KW combi is way over the top. I have a 10l/min flow, and a ~25KW combi was the recommended size. Opted for a (nominal) 30KW as I wanted a bit of spare capacity for when I fit a booster pump. This particular boiler is good for 12l/min according to the manufacturer's spec sheet. But I suspect a 32-35KW would be better.

casper_gutman

We have a combi in a five bed house. It's fine for us.

The choice between a combi and a system boiler doesn't really depend on the size of the house but on how you use hot water. A boiler powerful  enough to give instant hot water at a decent flowrate for even a single tap is probably powerful enough to heat just about any house.

The limitation on ours is that it will only really allow is to run one hot tap at full power. We have one shower fed from the boiler and one electric shower.

Albermarle

5) Swap your existing 'vented' hot cylinder for an 'unvented' type. Unvented are supplied by the mains, and deliver hot water at mains pressure and flow. But, since yours are carp in both regards, that is the last thing I'd do. Cost - along with the required new boiler - £4k upwards

When we had a loft conversion, we had to get rid of the cold water tank in the loft. As we were becoming a 4 bed/3 bathroom house with 4 people, the plumber said a combi would be inadequate, and we should have a unvented Megaflo type system, which could deliver how water to multiple outlets at he same time. It was about 15 years ago.

It has never really worked like that and eventually I have realised that the problem is poor mains water pressure in the area ( similar to the OP) So we should probably not had this system fitted/recommended in the first place and is not recommended for the OP as you say.