This must be a common dilema!?

[dylan39]

Hello all!

I have just moved into a 1960s house, its got a good old floor standing boiler but as part of the comprehensive refurb. I intend to replace this with an up-to-date system.

Key motivations:
- Must be capable of running 2 showers at the same time (House will have bathroom and ensuite)
- Would make life a lot easier if I could eliminate/relocate HW tank
- Boiler must be concealed in a kitchen cabinet.
- Want to avoid shower pumps if poss...
- Dont mind tanks in the loft
- I would like to avoid adding a larger water main into house if poss...
- I want the right solution - not necessarily the cheapest...

System spec
- 15mm main into house
- 4bar static pressure
- 14l/min flow
- 4 bedrooms
- 16 rads

The first plumber quoted for an unvented sys. I get the feeling he was pushing this as it meant more work for him.
The second plumber went completely the other way and pushed for a combi. I am still not convinced, as one of my prime motives is 2 showers.
The third plumber sat on the fence and is going to go away and look at flow rates for different products.

- Can some of you guys in the know help me to at least eliminate the crazy ideas?
- Roughly what will the council charge to add a 28mm main to my property?
-

Thanks guys - All your input is greatly appreciated!

Cheers

 

[pauls]

i would go with what the first guy said a system boiler with unvented hwc this would suite your needs

 

[dontknowitall]

I nearly said that too - just didn't have the guts to say it before someone else did!!!

 

[peteisfishing]

I feel both systems would work, as you can get combi's with a 25 LPM flow rate, but the unvented would probably be the most common for a house of that size,

 

[pauls]

I nearly said that too - just didn't have the guts to say it before someone else did!!!

lol is was going to wait to see what replys came up aswell

 

[dylan39]

Wow chaps - very responsive!

As for the unvented, I am guessing with the flow and pressure I have that I will need to upsize my main to 28mm...?

Any ideas on the water-board (Aint it funny that thats a form of torture too!) cost for T'ing in at the main?

 

[ecowarm]

Wherever possible the main supply pipe should be in 22mm. The minimum mains water supply requirements should be 0.15 MPa (1.5 bar) working pressure and 20 litres per minute flowrate. At these values outlet flowrates may be poor if several outlets are used simultaneously, the higher the available pressure and flowrate the better the system performance [FONT=Arial Narrow,Arial Narrow][FONT=Arial Narrow,Arial Narrow]will be.[/FONT][/FONT]
[FONT=Arial Narrow,Arial Narrow][FONT=Arial Narrow,Arial Narrow][/FONT][/FONT]
[FONT=Arial Narrow,Arial Narrow][FONT=Arial Narrow,Arial Narrow]Taken from a megaflo instruction manual
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[Blackcatgas]

Alpha cd 50, WB 440, or my choice Viessmann 222f in the cylinder cuboard fed from a new main or a 50 gallon tank in the loft via a salamander csp 80 pump, (another option)

 

[dylan39]

Hi all, thanks for the input. I am surprised that no one mentioned a cold water accumulator (GAH Coldstream or similar) - I had a dig and came accross these.

They are available in pretty large capacities and theoretically enable a pressurised store of cold water in line to the system

Has anyone any experience with these (Coldstream/accumulators)?

thanks

 

[Reg Man]

Accumulators do work, but they take up an enormous amount of room. Best long term way forward, is get your water main upgraded to minimum 22mm and go for unvented option. It was mentioned about a break cistern and pump, but this to should be avoided as pump noise could be an issue and its a bit of a dogs dinner. Combi boilers with a high HW flow rate are good but it looks like your mains still require an upgrade if you only get 14l/m. You may still be dissapointed with the HW flow rates if you have a combi, depending on your shower fitting demand.

 

[dylan39]

Hmmm, well not really the answer I was looking for because if I went for the solution you suggest then cost would be approx:
£300 for waterboard to estimate the cost of the work
circa £2000 for the waterboard to T into the main
£500 for the builder to dig the channel across the drive
£500 to reinstate drive
..thats £3300 before I've even touched the boiler! - URghh!
then £4500 for the boiler and associated plumbing.

Space really is not an issue - I have loads of wasted cupboard space and underfloor in this place.... accumulator for my reqs is about £700.

In all honesty I reckon its looking increasingly likely that I will go the route of standard boiler and vented sys with pumps. Sure pumps arent great, but TBH they work and the price differential is just SO high that I would have to be loopy to go unvented... (total cost circa £8k - woah!)

dp

 

[Gray0689]

You can still go unvented cwsc in roofspace and pump from cwsc to unvented cylinder this is what I would go for
A good grundfos booster pump
You get the best of both worlds then and don't need to upgrade the mains

 

[Reg Man]

Alot of work and cash for little gain. Might agree if the mains water pressure is terrible. Open sytem with a couple of shower pumps much simpler and cheaper.

 

[dylan39]

Alot of work and cash for little gain. Might agree if the mains water pressure is terrible. Open sytem with a couple of shower pumps much simpler and cheaper.

Must admit it ticks all the boxes ...

Shower pumps arent great, but they sure beat Saniflo macerators - they really pain me!

That said, I have a sewage stack access problem and short of a saniflow i am almost out of ideas!

dp

 

[HoodedClaw]

I was told that you cant/shouldn't put a combi in if there are 2 bathrooms, more so if 2 showers. In my experiance though I have found my Rehma deals well with the shower (16" head) and taps/DW/WM on. as long as its a decent thermo valve it just drops the pressure a little. Course the mains pressure would need to be good!

As all the experts said - a system up into loft would cope.

Will be interested on the mains size upgrade cost?

 

[tr7dan]

Just because you have a combi doesn't mean you can't have a hot water cylinder as well.

I have a similar sized house ie 4 beds / 17 rads. The bathroom (with shower), kitchen and utility has hot water directly from a Baxi 105e combi. The en suite shower room from a tank fed high recovery superduty cylinder also heated by the Baxi combi on a seperate timed zone. The heating is also on three timed, thermostatically controlled zones. It works well and I've used this setup a few times on customers jobs. Combi's are cheap, reliable and powerful and you can create zones easily with a 2 port motor valve and timer/stat.

Dan

 

[Reg Man]

Good point. I like it.

 

[tamz]

Just because you have a combi doesn't mean you can't have a hot water cylinder as well.

I have a similar sized house ie 4 beds / 17 rads. The bathroom (with shower), kitchen and utility has hot water directly from a Baxi 105e combi. The en suite shower room from a tank fed high recovery superduty cylinder also heated by the Baxi combi on a seperate timed zone. The heating is also on three timed, thermostatically controlled zones. It works well and I've used this setup a few times on customers jobs. Combi's are cheap, reliable and powerful and you can create zones easily with a 2 port motor valve and timer/stat.

Dan

I first did this around 20 years ago when it was much cheaper to buy a combi than buy a 24kw regular (as they are called today). Just wire it to switch throught the gray and orange of the valves.

 

[stevejordan]

Wow chaps - very responsive!

As for the unvented, I am guessing with the flow and pressure I have that I will need to upsize my main to 28mm...?

Any ideas on the water-board (Aint it funny that thats a form of torture too!) cost for T'ing in at the main?

not sure where you are dylan , but yorkshire water wanted me to new 25mm mdpe pipe from my kitchen area run up my drive (which included digging up concrete drive , and leaving it at my boundry with cap on , THEN THEY WOULD COME AND DROP IN A STOPTAP CONNECT UP AND CHARGE ME .......................................... WAIT FOR IT..................... A MERE £1100 ........................ NOT CHEAP

 

[Reg Man]

Typical Utilities, don't think they have enough competition.

 

[stevejordan]

typical utilities, don't think they have enough competition.

reg - monopoly springs to mind mate

 

[dylan39]

Monring gents

I did actually mention the cost to T-in. It makes £1100 seem cheap! They wanted £300 TO ESTIMATE THE COST.
Then they wanted between 1500 and 2000 to do the T. Of course i would have to sort the work on my land.

Hence the discussions about accumulators etc.

I have listened to all opinions, and I think for all round cost and flexibility I will go for a nice new little boiler, new HW tank, Shower pump (to run 2 showers) and some stats on the rads. Flow will be great (so theres a small pump noise!), costs will hopefully be circa £3000 for the lot versus around £8k to do the full unvented system properly.

Unless Im missing somethign its a no-brainer!

Also stand a chance of getting it b4 the new year!!

Then its on with the kitchen, bathroom, ensuite, basement, etc etc...

 

[metaldust9]

wouldnt bother with a combi unless is big ie baxi duotec 40 and that only give 16.5 litres a min probs go for worcester 550 floor standing probs do the job

 

[dylan39]

wouldnt bother with a combi unless is big ie baxi duotec 40 and that only give 16.5 litres a min probs go for worcester 550 floor standing probs do the job

Cheers, but pretty sure I wanna go with std condensing boiler now and vented sys.

dp