Why did my plumber install a Combi boiler, when I asked for a System Boiler?

ThisIsWeird

Section62 said:

ThisIsWeird said:

...

Do you have Legal Protection in your house insurance?

First things first.... does the plumber know the wrong boiler has been fitted, and what does he say about swapping it?

NO!

SUE SUE SUE! Then negotiate.

Sorry - came over all Trumpian there :-(

Flugelhorn

I hope there isn't someone else who was expecting a combi and found that somehow the one they got fitted doesn't produce any hot water 

ComicGeek

For example, the WB 4000 25kW combi is exactly the same physical size, output, efficiency, circulation pump etc as the WB4000 24kW system boiler in heating mode. They have deliberately made them all the same for mass production and flexibility. So certainly some cases where there is very little real difference.

I would be annoyed if this happened to me after specifically asking for a system boiler, but I would probably accept a small discount rather than force a replacement - possibly as free servicing for a few years... 

jj_home_80

Could it be that a combi boiler was easier to get or cost was the same? Not sure if it makes any difference for you as the user. As long as the efficiency is there and you weren't asked to pay more for it.

saintpatrick

Sorry for late replies - apparently I broke forum rules using my real name, so Admin had to step in and change it.
 
I appreciate the interest folks, I do, so I’ll answer the questions in the order in which I see them 

Greenstar 4000 24kW System was the item I showed my plumber and asked for - the agents don’t sell to public, only to trade, so the plumber bought the boiler and brought with him on the day of installation.

Greenstar 4000 30kW Combi (Model number GR47001W 30 C NG) was the item installed.

As of yet, I haven’t called the plumber to discuss it with him - so he doesn’t know I’m concerned or thinking of swapping it. I wanted to be prepared and think through any angles beforehand, but it could just be an error of course. I do have to consider if the new hole in my brickwork (see the white pipe with the black angled connection exiting the property wall in the photo uploaded) will remain redundant if he does swap it out - then I’m going to be sore about that too. 

I need to check my home insurance, but photo of pipework below…

Yes - I checked the stats of both boilers available to view on the Worcester Bosch website, and the efficiency, kW output, British Thermal Units, dimensions, appearance are the same

I should certainly try to find out if he intends to pocket the difference (~£200) or to pass that on…

ThisIsWeird - “I presume the extra pipework is a cold mains supply, and a DHW outlet going to this 'tap' you mention is required - 2x15mm pipes?” …I’m not sure, but the water pressure is 12.5 litres/min to the cold kitchen tap at present if that is helpful

As for the extra pipework - the photo will show that… I can only assume the DHW outlet is plumbed to the existing cylinder upstairs, as I use the heating control to order HW, and 30 mins later I can have a hot shower as usual… The tap that should be fitted as per W-B tech support would feed off the instant Combi HW function, so that this side of the boiler can be tested during servicing. 

W-B didn’t offer an explanation of why the plumber may have done this - the plumber is (or certainly has been) accredited with W-B - but I think tech support said they had heard of this practice before

FreeBear - I don’t knowThe W-B website states that this Combi has a ‘wide power range helps to reduce gas consumption and lower energy bills’ if that is helpful

ComicGeek - I’ve checked and the models I’ve quoted above for System & Combi are similar in performance

FreeBear

saintpatrick said: As for the extra pipework - the photo will show that… I can only assume the DHW outlet is plumbed to the existing cylinder upstairs, as I use the heating control to order HW, and 30 mins later I can have a hot shower as usual… The tap that should be fitted as per W-B tech support would feed off the instant Combi HW function, so that this side of the boiler can be tested during servicing.

Looking at the pipes from left to right at the back of the boiler, you have -

• Condensate drain
• CH flow
• DHW outlet (unconnected)
  
• Gas supply
• Cold water feed (unconnected).
  
• PRV overflow
• CH return.

Cold water is linked to the CH return by that short length of flexi hose.

If this boiler were to be swapped out with a system boiler, all the pipes would remain, including the white plastic condensate pipe.

A couple of observations - That Danfoss unit is a tad too close to the CH flow pipe. It will impact on the long term reliability. And I really hope it isn't a thermostat... To be fully compliant with current regs, it should really be a smart(er) programmable thermostat that talks to the boiler. Being programmable would allow you to set different temperatures throughout the day/week (potentially saving you up to 15% in gas consumption). And if it could talk to the boiler, adjust flow temperatures as the heat requirement of the house varies (another 5% saving in gas consumption). A dual channel control would also be able to increase the flow temperature automatically when heating the DHW tank (priority DHW) - Another big saving on gas consumption.

Oh, and the installer should have put some sealant around the pipes (and cable) where they go through the wall. Looks neater, and will stop any draughts coming through if you have a breezy cavity.

The WB Greenstar 4000 is a very capable boiler. Both the system and combi will modulate down to an impressive 3-3.3kW. Also rated to operate at a 40°C flow, 30°C return - If you have sufficiently large radiators and can run at a 40°C flow, efficiency should be around 96%.

ThisIsWeird

saintpatrick said:

Greenstar 4000 24kW System was the item I showed my plumber and asked for - the agents don’t sell to public, only to trade, so the plumber bought the boiler and brought with him on the day of installation.

Greenstar 4000 30kW Combi (Model number GR47001W 30 C NG) was the item installed.

As of yet, I haven’t called the plumber to discuss it with him - so he doesn’t know I’m concerned or thinking of swapping it. I wanted to be prepared and think through any angles beforehand, but it could just be an error of course. I do have to consider if the new hole in my brickwork (see the white pipe with the black angled connection exiting the property wall in the photo uploaded) will remain redundant if he does swap it out - then I’m going to be sore about that too. This is the condesnate pipe, common to both boilers - so not an issue (once it's tidied up a bit )

I need to check my home insurance, Useful for Leg Prot, just in case.
Yes - I checked the stats of both boilers available to view on the Worcester Bosch website, and the efficiency, kW output, British Thermal Units, dimensions, appearance are the same. Cool.

I should certainly try to find out if he intends to pocket the difference (~£200) or to pass that on. I think they should, certainly if the two boilers are 'different' in any notable way. At least compromise. Although, if it turns out that the two boilers are essentially identical in performance, size, relaibility, efficiency, and features, then I guess 'all' they've done is find the boiler you were after but cheaper, so perhaps not! If their policy is to quote for the more expensive System, and then always fit cheaper Combis, then they are trying it on as an unethical policy.

ThisIsWeird - “I presume the extra pipework is a cold mains supply, and a DHW outlet going to this 'tap' you mention is required - 2x15mm pipes?” …I’m not sure, but the water pressure is 12.5 litres/min to the cold kitchen tap at present if that is helpful The DHW flow rate has nothing to do with the boiler - it's provided by your incoming mains or Cold Tank in the loft.

As for the extra pipework - the photo will show that… I can only assume the DHW outlet is plumbed to the existing cylinder upstairs, as I use the heating control to order HW, and 30 mins later I can have a hot shower as usual… The tap that should be fitted as per W-B tech support would feed off the instant Combi HW function, so that this side of the boiler can be tested during servicing. Neither appear to be fitted.

W-B didn’t offer an explanation of why the plumber may have done this - the plumber is (or certainly has been) accredited with W-B - but I think tech support said they had heard of this practice before. I understand it is done - I've certainly read about examples. Whether it's good practice, I kind of doubt it.

FreeBear - I don’t knowThe W-B website states that this Combi has a ‘wide power range helps to reduce gas consumption and lower energy bills’ if that is helpful

ComicGeek - I’ve checked and the models I’ve quoted above for System & Combi are similar in performance

See comments in bold above.

There are currently no 'extra' pipes there over that of the System equivalent. Which goes against what you reckon W-B said was a requirement in your first post - ie there should be a mains water supply, and a tap or valve on the DHW outlet. This is possibly a concern - you should clarify with W-B (send them that pic if needed); does a Combi boiler, when used as a System boiler, still require a mains cold water supply, and a DHW outlet terminating in a test tap or valve? I don't know the answer to that, but W-B should confirm. If it's 'yes', then yours would appear to need adding.

Either way - System or Combi - the vast bulk of that plumbing is unavoidable and common to both; it will require disguising if you wish it to be. Obviously the most awkward part is the Mag Filter, and possibly that could have been mounted inside the base unit instead, but that would make it more awkward to access. Personally I'd be looking to make/have made a free-standing L-shaped panel, perhaps disguised with a spice rack mounted on the front? Or, just plain. Even that simple task is made more awkward by the poor location of that Programmer.
As FreeBear asks, what other controls have been fitted? All I can see is a mains power cable going from that FSU to the boiler, and a 'control' cable coming from the Danfoss to the boiler - no cable going towards a room stat, or wireless receiver? In which case, that is the most simple of 'timed' setups, with the boiler not being told when either the CH or DHW is 'satisfied'. In which which case, that installation is not compliant.
Even worse, do you know if the WB System boiler has 'Hot Water Priority'? (I'll try and look later). I would consider this to not only be an essential feature on any new System/Heat Only boiler, but absolutely expect it to be set up with suitable controls on a new installation.
What HWP does is to tell the boiler to issue its flow at different temps, if required, for CH and DHW. The DHW, for example, will require a flow temp of around 65oC, possibly more (the higher, the faster the cylinder heat up), in order to get the hot cylinder up to a safe ~60oC in reasonably quick time. You may even want the flow higher than this, if you are after a quick hot water refills - say with repeated showers in the morning, for example. But, since the boiler is set up to only deliver one fixed output temp, this 65oC+ flow could be too high for efficient running of your CH; the lower the CH flow temp, the more efficiently the boiler runs = energy savings.
To clarify your point in bold above, the instant-delivery of DHW that you have from a combi boiler has been completely disabled on your boiler. Hence, your '30 minute wait and then you have hot water' is by the boiler heating up your hot cylinder, using the exact same flow as it sends to your CH.
Will your boiler work as currently set up? Yes. 
Is it currently set up correctly with no mains supply, and no test valve on the DHW outlet? I don't know, but W-B seemingly says no.
Is your boiler currently installed to get the most efficient use of energy? Not from what I can see.
Is it even compliant? Not from what I can see (but could you confirm what other controls are fitted, please?)
All these things can be corrected.
But, the biggie afaIac, is, does the System equivalent have HWP? If so, I would personally not accept this combi compromise, unless it, too, can be set to provide this feature. 

Andy_L

my guess would be that the son cocked up & installed the wrong boiler, being confused by the fact that the combi had the "Same efficiency, kW output, thermal units, size, branding" as the system boiler 

ETA: or that the wrong one was ordered/delivered for the same reason

twopenny

It's worth asking them politely in the first instance.

As in 'I seem to have the wrong boiler' 'why have you instaled a combi when I asked for a system' and see what they say.

It's far more likely that there was some mix up and if they've discovered they have a 'wrong boiler' left over they are keeping their heads down and waiting for you to comment.

See if there was a reason...........then take it from there.

Meantime see if it works fine for your way of living. If it does I'd be inclined to see if you can get a discount for installing the wrong one - all in the nicest possible way in the first instance.

ThisIsWeird

SaintPatrick, I'd ask W-B to confirm a couple of things;

1) Any drawbacks in using a Combi boiler as a System boiler? If used as such, does it need a mains supply and a DHW test outlet?

2) Does the Greenstar 4000 System boiler have a Priority Domestic How Water setting?

Based on the answers, I'd determine whether it was 'take it out and give me what I asked and paid for'.

Interesting:

https://youtu.be/RJCGOtDLuNQ?feature=shared