Heating upgrade - opinions on these options please?

[dormermike]

Hi All

I need to upgrade an old open vented system as I need to remove all the tanks etc from an upstairs room, and have space downstairs to locate a new cylinder if needed, next to the existing floor standing system boiler.

I've had 3 firms out to quote, one gave two options (hence the four prices below), and each has been saying the other brands are not as good as the one they install. None have done a heat loss calc, and two stated the incoming mains pressure is "good" at around 20-22 litres and the third said it was "rubbish" at 15 litres. All existing rads to remain, and 2 of the 3 said there is never an issue pressurising an old gravity system but the third said its a small risk, but the leaks are usually easy to spot.

Hope its ok to show prices, and these are all for exactly the same job description (change pipework to suit unvented, and replace boiler, 3 bathrooms, 5 bedroom, 4 occupants).

Vaillant Ecotec+ 625 system boiler
Vaillant UniSTOR 250
Vaillant Sensocomfort controls
£6400

Worcester 4000 18KW
250l solar cylinder
Worcester Smart system
£6200

Viessmann 222-f 25kw (no controls specified)
£5600

Viessmann V100 25Kw system boiler
200L unvented indirect cylinder
No controls specified
£4600

Regarding incoming flow i noticed the 15 litre was done with a restriction on the outdoor tap and my own flow tests have shown 18-22 litres so i'm pretty sure that is probably representative of incoming flow.

Opening the floor to opinions on these quotes and brands as i'm completely stuck. There is no issue with space, but the 222-f appeals because its a nice looking unit (vanity eh) and also quiet. I am not a fan of noisy pumps etc. Downside is losing heat and DHW if it fails.

Thanks


edited to clarify - there are no rads being changed, only plumbing change is around the boiler and decomm the old tanks etc.

 

[fixitflav]

None have done a heat loss calc,

What's the output of the existing boiler? If that heats the house properly, no need to go bigger. You might even feel the existing is oversized so go down a size.

 

[dormermike]

What's the output of the existing boiler? If that heats the house properly, no need to go bigger. You might even feel the existing is oversized so go down a size.

Its an ancient boiler, non condensing. All the suggested boilers above seems to be a similar output of each other. I don't live in a mansion, so 24kw probably OK.

I'm really more interested in the pricing (seems high to me) and general opinions on the boiler solutions themselves. Is one particularly to be avoided, or better than the other? I've read about 222F being the dogs danglies but also is a compromise considering its an all-in-one package vs. a immersion enabled unvented cylinder, for example.

 

[fixitflav]

Its an ancient boiler, non condensing. All the suggested boilers above seems to be a similar output of each other. I don't live in a mansion, so 24kw probably OK.

I'm really more interested in the pricing (seems high to me) and general opinions on the boiler solutions themselves. Is one particularly to be avoided, or better than the other? I've read about 222F being the dogs danglies but also is a compromise considering its an all-in-one package vs. a immersion enabled unvented cylinder, for example.

Sorry, no idea about prices, I'm just a DIYer. But if your place is anything like typical 3-4 bed semi, 24 kW is oversized. 15 kw likely to be plenty, but better to do do a proper assessment.

 

[dormermike]

Its a 5 bed detached as it says in the first post. Thanks.

 

[fixitflav]

Its a 5 bed detached as it says in the first post. Thanks.

OK, missed that, mea culpa!

 

[muggles]

Unless it's unusually draughty or unusually well-insulated, 1kW per radiator gives a decent-ish guide. It has been a stipulation of Part L of the Building Regulations for over a year that a full room-by-room heat loss calculation must be carried out prior to replacing a boiler.

As for which one of the given options to go for, I'd start by discounting anyone who doesn't know how to properly carry out a flow rate test. That's a fairly basic gap in knowledge. The 222F is a nice looking unit, but you only get 7 years warranty as standard on the cylinder part vs 25 years with a separate unvented cylinder. The latest version of the Vaillant ecoTEC is a good unit, but if you can get away with a 20kW boiler the modulation is much better than the 25kW. The Worcester will be OK provided they're fitting the optional integral diverter valve kit to allow the boiler to run hot water priority.

 

[dormermike]

Thanks Muggles. 15 rads currently but will be installing underfloor heating (approx. 50sqm) in near future.

The Vaillant and Worcester guys were both off the Heatgeeks site, and neither did a pressure test but the Vaillant guy was the one who got the flow rate snafu. I asked both the heatgeeks guys about heat loss calc and the one shrugged it off and said its fine, and the Vaillant guy said I could do it if I wanted, but its an all day thing and will be the same result.

The Veissmann guy was the only one to do both a flow rate and pressure test.

Its a minefield.

PS yes the Worcester guy mentioned DHW priority and also its a solar cylinder for faster recovery.

The Vaillant guy was probably my favourite as he seemed to know his stuff, but £6k is a lot more than I was expecting, i must admit. I know its hard without seeing the job, but is this ballpark about right for the conversion of vented to unvented and fresh boiler & cylinder?

 

[muggles]

Probably not far off but depends on how much additional pipework is needed really. The last one I did cost more than that, but there was a lot of additional pipework to do and the whole job took 14 days. Bit disappointing that some Heat Geeks are taking that attitude

 

[dormermike]

All 3 said its 2-3 day job, and reusing the existing pipework. Where the pipework surfaces up in the upstairs for the tanks, they are cutting at floor level and joining up the 22mm pipes. The rest of it is all there, in a dedicate 2m x 2m utility room right next to the main bathroom. I don't think there is a huge amount of new pipework from what they've said.

and yes, i'd had higher expectations of heatgeeks too tbh.