Baxi Bermuda 57/3M flow rate

[jmw5678]

Hello,

I have a Baxi Bermuda 57/3M back boiler - approx 10 years old.
I have TRV fitted to all rads, dont seem to be any problems with this but am thinking of fitting an automatic bypass valve before selling house.

Before fitting, I need to know the min flow rate for the boiler, but cant seem to find this information anywhere on the manual. Anyone have any suggestions? Do back boilers need a min flow rate?

Thanks

 

[petit_pablo]

What type of system do you have? 3 port / 2 x 2 ports / gravity hot water pumped heating.

There shouldnt be a TRV on the radiator where the room stat is (if fitted)

 

[D_Hailsham]

Auto bypass valves are fitted for two reasons: because the boiler manufacturer specifies a minimum flow rate through the boiler; or, to control the change in differential pressure in the system due to TRVs opening and closing.

Minimum flow rates are only necessary on low water-content boilers with small heat exchangers, usually aluminium or stainless steel. These boilers usually have pump overrun. Older boilers, such as your Bermuda have a larger water content and cast iron heat exchangers, so they do not specify a minimum flow rate and, therefore, do not need a bypass.

This brings us to the second reason: controlling the differential pressure.

If the pump is set correctly, so it provides the correct flow rate when all the valves are open, then, when a TRV closes, the differential pressure will rise. The principal effect of this will be noise in the system, which will increase as more TRVs close.

If you decide to fit an ABV, just leave it on the default setting. This will ensure that the differential pressure does not exceed that specified by TRV manufacturers

 

[bengasman]

Hello,

I have a Baxi Bermuda 57/3M back boiler - approx 10 years old.
I have TRV fitted to all rads, dont seem to be any problems with this but am thinking of fitting an automatic bypass valve before selling house.

Before fitting, I need to know the min flow rate for the boiler, but cant seem to find this information anywhere on the manual. Anyone have any suggestions?

Yep, got a suggestion. If it ain't broke, don't fix it It has been working fine for 10 years, why change it when you are moving anyway????

 

[jmw5678]

Thanks for all the replies.

The system is gravity hot water pumped heating - and as far as I am concerned the heating and hot water works great.

The problem is, I replaced all the rads in the house a year or so ago, and fitted TRV to all of them (including the rad in the living room with the room stat). Only recently I have been looking more into heating and plumbing and was worried as I have no bypass on my system.

I haven't had any problems since doing this with noise or the boiler, but am concered I could be causing damage to the boiler, but as someone has mentioned above the baxi bermuda doesn't need a min flow rate.

So as suggested, if it not broken and working, I will leave alone. I may switch the trv in the bathroom to an open gate valve and that will act as a bypass then anyway.

 

[doitall]

What would be better is to put the wheelhead valve back on the radiators in the room with the roomstat.

 

[Agile]

The gravity connection ( ugg ) provides a heat outlet to the boiler.

The pump might have its output blocked if all the TRVs are off.

Contrary to popular perception this does not cause any problem!

Tony

 

[bengasman]

Gravity hot water, bit out of date, wouldn't like to swap gasbills.
Forget about the bypass, you have a 28 mm loop permanently open.

 

[jmw5678]

Gas bill not too bad, I recon £30 /month and as I am planning on renting the house out in January, dont want to spend much.

I did think of changing the living room rad back to open valve and it would be controlled by room stat - but if I leave the living room TRV on full (5) wouldnt this be the same?

bengasman - where do I get the 28mm loop permanenty open from? Am keen to know

Thanks

 

[kevplumb]

The system is gravity hot water pumped heating

the hot water loop is open

you don't need a bypass