Best Screwfix Boiler for 4 Bedroom Detached House

[Notch7]

foreign land

Essex

 

[ericmark]

What is a good boiler? One which uses less fuel, one that does not fail, one which can use existing installation. My boiler in this house is a low output at 18 kW, however it cycles, so clearly the radiators can't sink the heat produced.

The problem with a combi boiler is we often fit an over sized boiler for central heating so it can deliver enough DHW. And to me some combi boilers really cheat.

I had a Main 7 DHW boiler think it was around 18 kW and a separate central heating boiler, the central heating boiler was fixed output, but the Main 7 had a variable output, however there was a delay between switching on and getting hot water, and the old 22 mm pipes did not help, and the shower had to be turned full on or it would go cold, and it took an age to fill a bath.

Mother had a more modern Worcester Bosch combi, this had the option of using a small tank built into the boiler, so you could run a small amount of hot water, but she had to get rid of the power shower, not permitted with direct from mains supply, also she also had problems with shower starts cold goes hot then cold again then hot again as the hot water stored ran out. But she could turn the water down a lot further than my old Main 7 without boiler switching off, but it also needed an electrical supply to work, there was no mains supply to the Main 7.

This house also Worcester Bosch non modulating running C plan, and I can fill a bath so fast, but because it does not modulate I feel house going cold before it cuts in again, where with Mothers modulating gas boiler there was hardly any hysteresis. But with oil even if they do modulate it is not really enough to make any difference, gas however you can get 6 kW to 28 kW output, however no real point if the control does not allow the boiler to modulate.

So if we look at the Drayton Wiser with the OpenTherm option with linked TRV heads on every radiator then I am sure an OpenTherm boiler works very well, but same boiler with a Hive thermostat with no linked TRV heads may have a lot higher hysteresis and use a lot more gas, but both systems will likely work the same with an oil boiler.

So your not simply looking at a boiler, your looking at a whole system, and how that system suits your home. There is no best or worse, it is what suits your home, so an Eberspacher oil boiler may work A1 in a canal boat, but never seen one fitted in a house, they are small, and expensive.

I like the variable output of gas, but feel a LPG tank in garden is like having a bomb in the garden, so I use oil. But no point having a modulating gas boiler, then fitting a control system which will not allow it to modulate.

 

[ScottishGasMan]

In all honesty, your 20% discount is still going to work out a lot more expensive than trade price for boiler as SF is a bit of a joke for boilers. A proper heating engineer will need to survey the property and quote what you need, not what you get the best discount on.

 

[WoOt]

Hi ScottishGasMan, I did have two round last night. I have a preference for a Combi Boiler, which they thought wouldn't be a problem. They suggested a Combi that can deliver around 35 kW of hot water heat output.

All the below seem to fit the criteria, and as far as I can see there isn't a lot of difference between them.

The flow rate on the Valliant seems a bit lower than the other brands. And the Viessman seems to deliver as much as the other ones for a lot less money! The Baxi has the best flow rate, is a bit cheaper than the big names and comes with a free filter. The Worcester Bosch has the fancy name, I guess.

Any thoughts/suggestions? Am I missing something?

1. VIESSMANN VITODENS 050-W GAS COMBI BOILER (Stainless Steel Heat Exchanger)
   
2. BAXI 836 GAS COMPACT COMBI BOILER (Stainless Steel Heat Exchanger)
   
3. VAILLANT ECOFIT PURE 835 GAS COMBI BOILER (Aluminium Heat Exchanger)
   
4. WORCESTER BOSCH GREENSTAR 8000/35 STYLE GAS COMBI BOILER (Aluminium Silicon Heat Exchanger)

 

[ScottishGasMan]

35kw will give the same temp rise at the same flow regardless of the boiler make, the vaillant being lower flow rate will achieve higher temperature than boiler of same power at higher flow rate. As far as your use of it goes, you probably won't notice much if any difference between the different brands.

Would be worth seeing if the installer is registered to any particular manufacturer ie a vaillant advanced installer, or baxi works installer etc as they would be able to offer longer warranties on a make that they're registered with so getting more value for money

 

[WoOt]

Typically I see the point in going for the well known brands, but in this case I don't know enough about the subject to see any difference. So finding it hard to justify going for anything but the Viessman Vitodens 050-W 35kw.

 

[DP]

Me thinks the OP will be doing this themself or have a 'plumber' from a foreign land.

Andy

Do not knock plumber from foreign land, how do you know his work is going to be inferior?

 

[HERTS P&D]

DP, I have great respect for you as a fellow tradesman, especially reading many of your posts through the years, my post was more of a jest than being factual.

Andy

 

[WoOt]

The one guy came back saying I should absolutely avoid the Viessman, which surprises me as it won best boiler a couple years in a row. Is her right? Is it not a good choice?

 

[dilalio]

DP, I have great respect for you as a fellow tradesman, especially reading many of your posts through the years, my post was more of a jest than being factual.

Andy

I have some stories

In certain countries, it would appear Newton was wrong!

 

[ScottishGasMan]

The one guy came back saying I should absolutely avoid the Viessman, which surprises me as it won best boiler a couple years in a row. Is her right? Is it not a good choice?

You won't get a straight answer as everyone is biased for and against certain brands. Every boiler has its issues, just like every make of car. I dunno much about the Viessmans from personal experience though.

 

[dilalio]

As said again and again... Its more about the install than the appliance... And not just for boilers.

 

[muggles]

The one guy came back saying I should absolutely avoid the Viessman, which surprises me as it won best boiler a couple years in a row. Is her right? Is it not a good choice?

Personally I wouldn't fit any of the ones you've linked to, for different reasons in each case. You're not really comparing like with like with the Viessmann here though - you've put Baxi & WB's top of the range boilers next to Viessmann's bottom of the range budget option. The Vaillant is actually a rebadged Glow-worm Energy, and has poor modulation.