I need to replace our boiler which is now 10 years old and on its last legs. It’s a floor standing Potterton Powermax 115 and has been a right old bag of nails for the last 3 years.

I have a 3 storey 4 bed town house with 2 bathrooms and 12 radiators. I’ve been told to stick with Vaillant or Worcester Bosch and would need a decent flow rate. Anyone with good boiler experience that can give me some recommendations please? Cheers!

Worcester Bosch are excellent. I’ve had a CDi Compact fitted after an old boiler failed and it’s been excellent so far.

Vaillant over WB everytime for me. If your replacing a powermax your probably going to want to replace it witbh a system boiler and unvented cylinder rather than a combi. Btw glow worms are made Iin the same factory as the vaillants designed by vaillant just not as expensive.

Vaillant over WB everytime for me. If your replacing a powermax your probably going to want to replace it witbh a system boiler and unvented cylinder rather than a combi.

Would a combi not be suitable then?

Viessmann for me.

It could be depending on occupancy and usage patterns but powermaxs do give a good flowrate when they work. If you want to run two showers at once for instance even the biggest combis would struggle. Plus the fact you would more than likely get a better turn down ratio with a smaller system boiler.

Do you have any specific system models in mind fluxhutchinson? What’s the turn down ratio?

Had an early CDI WB (year 2000) and things constantly went wrong. Access to some fairly key parts (condensation trap, diverter valve and expansion vessel really poor). Have a Vaillant now and so far quite impressed.

A combi is sized on hot water required so tend to have a bigger rating on gas consumption. Where as a system boiler is sized on heat load of the house plus an allowance for the cylinder.

Saying that though most modern cylinders have big coils for fast heat recovery. Your house might only require a maximum heating requirment of lets say 16kw. So you could put a vaillant 618 in. Little bit of room for expansion if required.

Turn down is basically what the boilers minimum rating would be. Because the full 16kw would only be rquired at peak load which is only a small portion of the year. The rest of the time it would require less than this. So the lower the boiler can modulate (turn down) the less it cycles on and off. I hope this is making sense.

Edit. Dont know if this against the rules please delete if it is.

Just noticed your in Northampton, I know some really good people out your way if you dont have a gas installer already email is in profile if you want to know more.