Help to understand quotes for new system boiler

Is there a kind person out there who can help me understand if these 2 quotes are comparable? One seems much longer than the other but with my practically non-existent technical knowledge, they both seem to be saying more or less the same thing. In a nutshell, is one offering more than the other or are they pretty much like-for-like? Many thanks!


Quote 1 - Vaillant ecoTec Plus 30 System boiler

Isolate supplies and drain down water.
Disconnect and remove the existing radiators, boiler and flue.
Supply and install a new Vaillant system boiler and flue to the Cupboard.
Supply and install a system filter.
Supply and install a new 250L unvented hot water cylinder to the Airing Cupboard.
Supply and install new radiators with thermostatic valves to 12 rooms.
Fill the system and flush out, refill with added corrosion inhibitor.
Carry out system water test and report back if there are any issues.
Removal of all waste from the site for recycling/disposal.
Set up and test of the whole system, including a full handover and explanation of the system and controls.
Commission and issue manufacturer's warranty*

Quote 2 - Worcester Greenstar 4000 System boiler 24kW

SUPPLY & FIT:
BOILER
A Worcester Bosch Greenstar 4000 24kw, wall-hung, fan flue, gas fired, ErP rated ‘A’ condensing, system boiler, to be sited in the
airing cupboard, complete with gas, water and electrical connections.

FLUE SYSTEM
Extend from boiler turret vertically, terminating externally in the approved manner, using a Worcester Bosch flue kit.


CONDENSATE DISCHARGE
Extend condensate pipework from the boiler to internal, complete with all necessary connections.

CENTRE RAD COMPACT RADIATORS
Locations and sizes to be confirmed with customer preferred locations.
These calculations are based on an outside temperature of -1°C and a boiler flow temperature of 82°C, to conform with the
requirements of BS EN442, 2003. One and a half air changes per hour per room. Under these conditions, these temperatures are
guaranteed.
Plumb in 13 new radiators complete with Danfoss thermostatic & lockshield radiator valves and necessary pipework connections
onto existing heating system, using copper pipe of adequate size, as necessary.

HEATING CIRCUIT IN SMALL-BORE (15 & 22mm)
A two pipe accelerated small-bore system, using copper pipe to BS 2871 and Hep2O plastic pipe to BS 2791, concealed beneath
the 1st floor and dropping down to the ground floor in the most practical manner, so as to hide as much pipe as possible,
concealed within chased walls (no allowances to re-plaster)

CONTROLS
A Honeywell twin channel timer complete with digital, room thermostat sited where necessary.
Electrician to quote for new spur for boiler and immersion supplies.

PUMP
A new pump is factory fitted inside the boiler.

WORCESTER FILTER
A 22mm Worcester filter unit sited adjacent to the boiler, plumbed-in complete with all necessary connections.

HOT WATER
A Worcester Bosch 210 litre unvented indirect cylinder to be sited within airing cupboard.
To run new 22mm cold main from stop tap location to maximise pressure.
To run new D2 pipe to external wall.

MANUAL SYSTEM FLUSHWATER TREATMENT TO BS7593
Introduce Fernox F3 cleaner and flush to drain inline with manufactures instructions.

GENERAL
Run gas supply from meter point, to the boiler, using copper pipe of adequate size, as necessary.
Make good to brickwork and plaster cut out during the course of the installation.
Complete all electrical wiring to heating controls. (Subject to the existing electrical installation being suitable. Some systems may
need upgrading to current safety standards at extra cost).
All rubbish and redundant materials removed from site and allowed for in this quotation.
Commission boiler, as per manufacturers instructions.
Inject system with Fernox Filter Fluid Protector which is specifically formulated to lift corrosion deposits and contaminants within
central heating systems to deliver the debris directly to the Worcester system filter.
System filled, boiler fired, tested and left in working order, for a total cost, including labour and all materials.

As a starter, unless your place is large, 24 kW is likelyto be oversized, let alone 30 kW. Have they done a heat loss calculation?

Yes, they've done heat loss calculations. It's quite a big house, very old and we have an open fireplace.

As above re boiler size I'd want to look at heat loss calculations.
They both seem to be offering what would be regarded a a fairly standard S plan system.
I would at least look a better controls and a boiler capable of hot water priority that could keep boiler in condensing mode most of time.

OK thanks. So if it turned out that the 24kW and 30kW boilers quoted for are too big, what implications would that have? More expensive initially or more expensive running costs or something else?

System (rad sizes) should be designed with a flow temp of 55*C not 82*C.

Awful everything.

I bet if you ask the bidder "Why" on any random point in either quote, they wont be able to answer you.

Template engineering at it's finest.

Absolute ****e.

Iddy said:

System (rad sizes) should be designed with a flow temp of 55*C not 82*C.

Click to expand...

My thought too

Murdoch77 said:

Yes, they've done heat loss calculations. It's quite a big house, very old and we have an open fireplace.

Click to expand...

Second is more thorough but first is offering a better boiler ( my choice). Then again WB technical backup is hard to beat.

Would I fit a Worcester in my place? I have got the Ecotec. Over the years it has needed parts changed but generally nothing drastic. Brass components inside. But then again, can repair either brand

What is the reason for this in the second quote - Do you have steep pipework by any chance or a one pipe system ?

HEATING CIRCUIT IN SMALL-BORE (15 & 22mm)
A two pipe accelerated small-bore system, using copper pipe to BS 2871 and Hep2O plastic pipe to BS 2791, concealed beneath
the 1st floor and dropping down to the ground floor in the most practical manner, so as to hide as much pipe as possible,
concealed within chased walls (no allowances to re-plaster)

JackK said:

What is the reason for this in the second quote - Do you have steep pipework by any chance or a one pipe system ?

Click to expand...

I don't actually know. I guess it might relate to the fact we were considering moving the boiler upstairs. It's currently downstairs. No idea what type of pipes we currently have. I know they're copper - that's all.

Murdoch77 said:

if it turned out that the 24kW and 30kW boilers quoted for are too big, what implications would that have? More expensive initially or more expensive running costs or something else?

Click to expand...

I think we're erring towards the company offering the Vaillant Ecotec Plus but I'd like to understand the implications of having a boiler that's potentially too big. Can anyone please advise? Thanks.

The radiator sizing is very important and is cost relevant.

The latest regulations to size rads to suit heat pumps with a flow temp of 55C is very relevant for the future.

You seem to be getting a lot done and so it is important to get it done properly.

The TRVs could be cheap £15 ones or £30 Drayton good ones. That needs to be specified.

I am amazed that the second can be so bad and totally not complying with the current requirements. The first is so lacking in detail that it could end up as a very overpriced and poor job.

My view is that you should pay another RGI to check the detailed specifications before you make any decision. And have both quotes including the rad sizes so that you compare like with like.

Has anyone checked the mains water dynamic flow rate to see if an unvented cylinder is feasible?

If you are having new system and new radiators you could get a hot water priority system with radiators sized to suit low flow temperature yet able to reach target room temperature at say -3deg outside.

Ask about weather compensation

My new system has hot water flow at 80 deg and heating temp set by weather comp, but it’s usually around 30 to 45 deg. Aside from efficiency having radiators at low temps gives a very comfortable room temperature.

For no info look at YouTube urban plumbers and heat geek channels search for hot water priority

Murdoch77 said:

I don't actually know. I guess it might relate to the fact we were considering moving the boiler upstairs. It's currently downstairs. No idea what type of pipes we currently have. I know they're copper - that's all.

Click to expand...

Highly unlikely they're quoting a single pipe system. If they are, tell them where to go!
If the boiler and HW cylinder are both to go in the airing cupboard it must be a big one.
WB have quoted pipework 15 and 22mm, the other quote doesn't say, but worth making sure they heven't based on 10mm or even less (microbore).

Murdoch77 said:

Plus but I'd like to understand the implications of having a boiler that's potentially too big. Can anyone please advise?

Click to expand...

Mainly up-front cost, including possible need for a bigger gas pipe to meet the pressure drop regs. Might be a little less efficient as it will be working at a big turndown.
Does it have to be a system boiler? A heat-only is easier to troubleshoot in event of a problem. It also allows the option of a F/E tank instead of an expansion vessel. There are pros and cons with each and opinion in the trade is divided, but my preference is F/E tank.