Unvented cylinder with baxi Bermuda bbu

[SPC]

I've been asked if I can install an unvented cylinder with the current baxi Bermuda back boiler unit, guy doesn't want to change the boiler as it is working fine and hears some bad stories with some new boilers which is fair enough.

Currently it is pumped heating and gravity hot water.

Am I correct in assuming I can cap the 28mm gravities off, repipe the pumped side of the bbu so I have a main flow to the cylinder, 2 motorised valves, auto by pass etc and a feed back to the heating system making it a fully pumped system?

Haven't had time to ring the manufacturer yet but any input would be appreciated

 

[Fowlersrs]

Yeah of course you could do that, as long as you remember that the unvented cylinder needs control of that 2 port zone valve so that it can't overheat and you will be fine to leave the back boiler side on gravity and obviously the hot water side would be pressurised.

Bit of a dinosaur tech tho, if he's prepared to take an unvented cylinder why no heat only or system boiler? Oh I forgot the baxi lasts forever, however it is an open flued appliance, you might wanna point that out to him with regards to future safety

 

[macackau]

Replace it with a condensing baxi Bermuda! Seriously though don't, I've done one and will never do another.

 

[SPC]

So from the RHS of the boiler it currently feeds the heating system in 22mm pipe with a pump and on the LHS side is 28mm gravity to the cylinder. Can I reuse these 28mm pipes, put an additional pump on that with 2 port valve and auto bypass etc to save re piping at the side of the boiler? Has anybody encountered a similar situation and what solution did you come up with??

 

[SPC]

I spoke with baxi technical this morning and they said it wouldn't work efficiently by putting an additional pump on the existing gravity pipework as the pump would pump the water through the 28mm pipework too fast for the boiler to heat it properly. They said best thing to do is cap the 28mm gravity and pipe it like a normal s plan from one side of the back boiler unit so that's what we did and all was good

 

[tamz]

If the baxi is old enough to have flow and returns off both sides scrap it. Its around the same age as a mark 4 zephyr...................
One of these, and when was the last time you saw one running around town

 

[tamz]

If you or they are insistent on keeping it it will need to be repiped to a 2 pipe off the boiler.
Pump on the return and changed to a combined feed expansion would minimise what needs swapped but its too late to explain that lot if you don't know already.

 

[SPC]

Why does the pump need to be on the return? That was also the original position but I swapped it. Next to the boiler I had the pump on the flow into a tee, 2 port for heating and connected back into heating circuit, other section of the tee went upto the cylinder utilising 28mm gravity pipes (capped at boiler side) auto bypass and 2 port on unvented cylinder. Cold feed went into the flow and open vent was on the return side. Aav on the cylinder return. Does that sound good or am I missing something?

 

[Billy Bob Bob]

piece of pish to do,simple answer convert it to s plan,pump on the flow