vaillant or worcester boiler

[diyworker]

I meant the score of reliability. Two best brands turned out as Vaillant combi and worcester.

The "Which" magazine gives the best two brands as vaillant and WB.

I thought it was the Potterton HE boilers?

 

[D_Hailsham]

I meant the score of reliability. Two best brands turned out as Vaillant combi and worcester.

But that's based on the experience of subscribers to Which? and is the result of surveys asking people about problems they have had with boilers. So the fewer complaints Which? receives about Brand X, the better it must be. It takes no account of the market share or the number of people who don't bother writing in and complaining.

The other problem with their figures is that it is drawn from a particular class of boiler owners, mainly well-off middle class who can afford the annual subscription to Which?.

 

[looneyfitter]

the 35 viessmann for example will modulate right down to 5kw

no it wont

My Bad its 8.8kw @50/30 & 8kw @80/60 on the 35kw

19kw comes down to 4.8 & 4.3.

Never the less the 35kw would still be fine in most installations.

http://www.viessmann.co.uk/etc/medi....File.File.tmp/Technical Guide 19 to 35kW.pdf

 

[D_Hailsham]

its 8.8kw @50/30 & 8kw @80/60 on the 35kw

19kw comes down to 4.8 & 4.3.

Never the less the 35kw would still be fine in most installations.

There will be many houses which do not even need 8kW maximum output.

Now that houses are becoming better insulated, boiler manufacturers need to produce models which are more suitable, i.e with minimum outputs going down to 1 or 2kW.

 

[looneyfitter]

I appreciate that, but thats more new generation housing and not current. With the new generation, thats where heat pumps with solar HW and the likes will come into play.

Older houses are alot more in-efficient as we know. Also this guy is heating a cylinder too, so there could be anything from 10-20kw there on its own.

Every house is different i suppose.

EDIT by current i mean 10+years old

 

[Agile]

Older houses are alot more in-efficient as we know. Also this guy is heating a cylinder too, so there could be anything from 10-20kw there on its own.

Does that mean that you would therefore fit a 20 kW boiler just to reheat the cylinder for 20 min once a day?

Ignoring the energy efficiency advice you should have learnt on your course that you allow 2 kW for water heating!

 

[D_Hailsham]

Older houses are a lot more inefficient as we know.

Which is why the Government is pumping a lot of money into improving the insulation of older properties.

Also this guy is heating a cylinder too, so there could be anything from 10-20kw there on its own.

As Agile says, the normal allowance for a HW cylinder is only 2kW. This is because the water is frequently heated overnight, when the CH is off. Furthermore the water only needs to be raised in temperature by about 10C, the differential on typical cylinder stats.

If you have a cylinder and a boiler with weather comp, there is not really any need to allow any extra for hot water as the system will act like a combi - HW priority.

I have visited new build 4 bed, 2 bathroom houses which have a 15kw system boiler and a large unvented cylinder.

My house, which is about 20 years old, has the original 14kW boiler. It now has double glazing, cavity and loft insulation. The heating requirement is now about 8kW. I'm just waiting for the boiler to pack up so I can fit a smaller more efficient one.

 

[gasafengineer]

As Agile says, the normal allowance for a HW cylinder is only 2kW. This is because the water is frequently heated overnight

Furthermore the water only needs to be raised in temperature by about 10C, the differential on typical cylinder stats.

most programmers are timed to go off around 9pm.


10 degrees? , which would have the hot water temp around 30 degrees?

Good job you won't be sizing my boiler , wife would kill ya come heating season.

 

[looneyfitter]

I would never only allow 2kw for HW, advice or no advice... I allow 8-10kw minimum on a 3 bed house with say 1 bathroom, kitchen etc.

It all depends how many people live at the house/ life style etc. Like ive said the boilers are modulating so it will ramp down anyway. And were not talking about Heating hot water only all year round here, were talking on the hole.

On the same note then, would you only allow 2kw and then make the customer wait 1 1/2 before they get hot water once it runs out?

Swings and round abouts.

edit i also agree that 8-10kw is not very energy efficient but on the same note you dont want your customers complaining that it takes forever to get hot water once its gone.

 

[looneyfitter]

Older houses are a lot more inefficient as we know.

Which is why the Government is pumping a lot of money into improving the insulation of older properties.

Also this guy is heating a cylinder too, so there could be anything from 10-20kw there on its own.

As Agile says, the normal allowance for a HW cylinder is only 2kW. This is because the water is frequently heated overnight, when the CH is off. Furthermore the water only needs to be raised in temperature by about 10C, the differential on typical cylinder stats.

If you have a cylinder and a boiler with weather comp, there is not really any need to allow any extra for hot water as the system will act like a combi - HW priority.

Which is why im suggesting he uses the 200w with weather comp... You cant go wrong. 5 bed house is gonna use more that 8kw.

Also its still hard to get customers to leave the hot water trickle charging so to speak.. They still think 2 hrs on is best.. Same goes for heating

 

[Agile]

I would never only allow 2kw for HW, advice or no advice... I allow 8-10kw minimum on a 3 bed house with say 1 bathroom, kitchen etc.

There are always some people who do not understand or will not accept the energy efficiency advice.

Perhaps you also it undersized cylinders so they run out of hot water too soon before the occupants have finished washing?

In your case it seems the requirement to attend the efficiency course did not achieve its objectives!

 

[looneyfitter]

I would never only allow 2kw for HW, advice or no advice... I allow 8-10kw minimum on a 3 bed house with say 1 bathroom, kitchen etc.

There are always some people who do not understand or will not accept the energy efficiency advice.

In your case it seems the requirement to attend the efficiency course did not achieve its objectives!

I did not say i dont understand it did i? I did not say i wont accept it either.... What i am saying is that the majority of customers, still cannot fathom that its cheaper to leave the heating on and runit in set back..

Same goes for HW, its cheaper to have it trickling i agree... But what that doesnt do is give good re-heat times which inturn makes the customer unhappy.. SO what are you supposed to do?

 

[looneyfitter]

And why did you edit the middle line? Were not talking whole installations here, were talking a new boiler only !!!!!!!!

How many 3 bed houses have you been to with 36x18 cylinders in? 1 Bath and its gone!!! Cos ive been to loads....

 

[D_Hailsham]

As Agile says, the normal allowance for a HW cylinder is only 2kW. This is because the water is frequently heated overnight

Furthermore the water only needs to be raised in temperature by about 10C, the differential on typical cylinder stats.

most programmers are timed to go off around 9pm.

What, for hot water?

Ours is on from 4am to 5am (before the heating) and then from 9pm to midnight (bath/shower time).

10 degrees? , which would have the hot water temp around 30 degrees?

We are talking about HW cylinders. The thermostat will normally be set to 60C (turn off temperature), so it will come back on about 10C lower, which is 50C.

 

[looneyfitter]

Mr hailsham, if that's the case with your timed hot water, then you may swell deduct another 2kw off your boiler size then seen as it's not used when the heating is on?