Which External Oil Combi Boiler?

[Possom]

Given that there's only about £100 difference in price in these two external combi oil boilers, and both are physically the same size, I guess may as well just opt for the second one, the E26C which has a higher flow rate of 22 L/min (compared with first option of 18 L/min).

House has 3 bedrooms and one bath.

Warmflow Agentis E21C external combi oil boiler 21kW
Flow Rate 18 L/min

Warmflow Agentis E21C external combi oil boiler 21kW | Wolseley

Looking for a Warmflow External Combi Boiler E21C? Order from Wolseley today - free delivery or click and collect available nationwide.

www.wolseley.co.uk

Flow Rate: 22 L/min
Warmflow Agentis E26C external combi oil boiler 26kW

Warmflow Agentis E26C external combi oil boiler 26kW | Wolseley

Looking for a Warmflow External Combi Boiler E26C? Order from Wolseley today - free delivery or click and collect available nationwide.

www.wolseley.co.uk

 

[Johntheo5]

Given that there's only about £100 difference in price in these two external combi oil boilers, and both are physically the same size, I guess may as well just opt for the second one, the E26C which has a higher flow rate of 22 L/min (compared with first option of 18 L/min).

House has 3 bedrooms and one bath.

Warmflow Agentis E21C external combi oil boiler 21kW
Flow Rate 18 L/min

Warmflow Agentis E21C external combi oil boiler 21kW | Wolseley

Looking for a Warmflow External Combi Boiler E21C? Order from Wolseley today - free delivery or click and collect available nationwide.

www.wolseley.co.uk

10.6LPM
Flow Rate: 22 L/min
Warmflow Agentis E26C external combi oil boiler 26kW

Warmflow Agentis E26C external combi oil boiler 26kW | Wolseley

Looking for a Warmflow External Combi Boiler E26C? Order from Wolseley today - free delivery or click and collect available nationwide.

www.wolseley.co.uk

Are you replacing a existing oil fired combi??, if so, you will be aware that these stated DHW flowrates are not continuous, these are normally qualified in the MIs by stating something like 22LPM at a 120L draw off with a dT of 35C, which means ~ 5/6 min, the heat store must then be re charged taking around 5 to 10 minutes depending on boiler output, during which time presumably, no DHW (or CH) is available.
Any 21kW boiler should give a continuous output of 8.6LPM at a 35C dT, say from mains at 5C to HW at 40C, and a 26kW, a continuous flowrate of 10.6LPM, I'm not familiar with combi boilers but @Exedon or others will advise if these flowrates are continuous if you keep the demand at or just below these flowrates once the store has been charged, just bear this in mind.

 

[Exedon]

First thing to say is we would never ever install a oil combi that began with a W.
I would suggest the flow rates quoted wouldn't be attainable for long, Grant claim 17 LPM for the 26kw which they can easily attain but of course will drop of if heat store completely depleted.

 

[Johntheo5]

In your opinion, if the DHW demand is kept at, or slightly below the output of the boiler, (10.65LPM from 26kW at a dT of 35C), should there be a continuous supply of DHW?. I presume that all oil fired combis are "stored" because the can't modulate and otherwise would cycle on/off with a small DHW demand causing temperature fluctuations.

 

[Exedon]

In your opinion, if the DHW demand is kept at, or slightly below the output of the boiler, (10.65LPM from 26kW at a dT of 35C), should there be a continuous supply of DHW?.

Absolutely if kept to that level you will get continuous hot water.
In practice it's normally only filling large baths that come close to depleting store.

 

[Possom]

First thing to say is we would never ever install a oil combi that began with a W.
I would suggest the flow rates quoted wouldn't be attainable for long, Grant claim 17 LPM for the 26kw which they can easily attain but of course will drop of if heat store completely depleted.

I can only think of two which start with a W. These, and of course WB.

What other brand do you prefer?

 

[Exedon]

Really prefer not to fit combi's at all if we can,but sometimes needs must.
We are Grant registered installer's have very few problems.
We have pulled out combi's from both W companies at 5 years old.
Plus the back up from them both leaves a lot to be desired.