New heating system annoyances

[Harry Bloomfield]

But apparently you can turn the output down on the boiler to say 15kw which will in turn bring down the the minimum output to something more suitable for my system.

Will reducing the maximum, also reduce the minimum? I would not expect it to affect the minimum ouput.

 

[Stotty1]

Will reducing the maximum, also reduce the minimum? I would not expect it to affect the minimum ouput.

Interesting, they made it sound like it would reduce the minimum output.
I will have to clarify when they ring later and make sure they are not just fobing me off.

 

[muggles]

Interesting, they made it sound like it would reduce the minimum output.
I will have to clarify when they ring later and make sure they are not just fobing me off.

It won't. The minimum is fixed. Only the maximum can be adjusted

 

[ericmark]

You have a host of external controls, and the settings do matter. As already explained the boiler will modulate when hot water returns, and once modulated to minimum output it will start cycling (turning off/on) if the boiler initiates the cycling when it turns on it will be at minimum output, however if some external control like an on/off thermostat or programmer turns off boiler it will turn on again at maximum output.

But the boiler needs external controls, it can't work out from the return water once switched off when to turn back on again, so any boiler not just WB needs some thing to tell it when no longer required. Or more to point, when it is required again.

I am not a heating engineer, I am an electrical engineer, so if one of the heating engineers jumps in then listen to what they say. There is a WB wall thermostat which can modulate the boiler, no idea if it will fit on yours, but if the on/off wall thermostat is set to compliment the TRV valves you can get it to work reasonably well without a modulating thermostat.

I did it with mothers house, and I will not pretend it was easy, the wall thermostat was in the hall and set to 19°C the TRV in the hall set to 3.25 which is around 18°C, so the hall would on start up, or opening front door heat up to 17°C fast, but then the TRV started to close so those last 3°C took a long time, in winter likely never reached, in spring it would switch off boiler only on warm days.

All other rooms also controlled by the TRV's and so I could work out the temperature I swapped 4 of the heads to electronic heads, so could program temperature of the rooms, and once set yes it worked well, 3 out of 4 rooms were spot on, the 4th room had a bay window and sun in the bay window could cause over shoot, but can't blame system for that.

In hind sight and hind sight is easy, I did not select best wall thermostat or TRV heads, but all down to how much you spend, and it seems most central heating systems are designed by near enough engineering, not spot on, and you have to decide how far to take it.

 

[Stotty1]

It won't. The minimum is fixed. Only the maximum can be adjusted

Thanks for confirming @muggles, I will have a nice chat with WB later.

@ericmark I will bear that all in mind, thanks

I have been dwelling on the situation and to be honest, the more I think about it the more I feel I shouldnt have to spend more money on fixing the issue.
They came around and took all the measurents and house details, they are the experts, in my eyes they should have fitted the best boiler for our house.
So I'm starting to think I may argue the issue with the installation company first.
(It may not work but its worth a try)

They even stated they expect our gas usage to drop.

Looking back at the quote, they offered the WB 30i first, then changed the boiler to the 32cdi as an upgrade, an incentive to choose them.
I'm not sure how good the 30i is (struggling to find the minimum output) but I'm guessing that we are worse off energy wise, with the "upgrade".

Thanks guys you have all been a great help

 

[muggles]

The 30i's minimum output is 7.14kW, so you'd have been no better off I'm afraid.

I fear your problems may have started with a slight fixation on WB boilers which, despite what a certain well known consumer magazine would have you believe, are far from being the best buy on the market. As you're now discovering, they generally suffer from poor modulation across the range, making them unsuitable for a lot of homes. They spend a lot of money on marketing, and have among the best aftersales care going, but the boilers themselves don't seem to get quite the same level of attention. I was recently told by another boiler manufacturer that they were undercut by WB when trying to gain a contract with a big national installation firm. I'm told they went in at mid-£300's per boiler and couldn't match WB's bid without making a loss...WB were presumably still in profit at their price. (Note to those who know my preferred boiler manufacturer...no, it wasn't them )

Anyway, I digress... Good luck challenging the installation firm on the suitability of their recommended boiler for your home. It's something people need to start doing much more, as there are tens or possibly even hundreds of thousands of people in similar situations to yours. Unfortunately the vast majority just accept what they're given and keep their rose-tinted spectacles firmly affixed against any disappointments with performance. They don't, for the most part, know any better and never will unless they ask the right people. There needs to be a paradigm shift in the industry towards specifying the right boiler for each individual home, but it needs to be led by those same consumers who are totally unaware of the differences between a good installation and a bad one on a technical level. Some, like you, become aware after the installation, but I don't know of a single case where someone has successfully challenged an installer on the basis of poor appliance selection. Make it happen if you can, you could be the one to open the floodgates.

 

[Harry Bloomfield]

I fear your problems may have started with a slight fixation on WB boilers which, despite what a certain well known consumer magazine would have you believe, are far from being the best buy on the market. As you're now discovering, they generally suffer from poor modulation across the range, making them unsuitable for a lot of homes. They spend a lot of money on marketing, and have among the best aftersales care going, but the boilers themselves don't seem to get quite the same level of attention. I was recently told by another boiler manufacturer that they were undercut by WB when trying to gain a contract with a big national installation firm. I'm told they went in at mid-£300's per boiler and couldn't match WB's bid without making a loss...WB were presumably still in profit at their price. (Note to those who know my preferred boiler manufacturer...no, it wasn't them )

I'm no expert, but.....

I would expect the minimum modulation level to account for all, or event a large proportion of that increase in gas. All boilers will at some stage hit the 'minimum is too much heat input' stage, especially in the autumn and spring when heating can be on, but heat loss in minimum. My own boiler (Vaillant) only modulates down to 5Kw, it's inaudible at its minimum, I have never noticed an cycling, rather it stays off for extended periods - though for the stle of house we are well insulated.

The past few weeks have been exceptionally cold and the OP admits his house is generally much warmer, these two things alone can easily account for a doubling in consumption.