If you have a Junkers Bosch Gas Heater with low and fluctuating pressure the ShowerPowerBooster is an ideal solution for boosting a single tap or shower.
A Junkers Bosch Gas Heater has a differential pressure valve which turns off the gas if the inlet pressure is too low. It also has a thermostat which regulates gas pressure to maintain temperature.
Differential pressure is created when a tap or shower is turned on but it the inlet pressure is too low it just will not turn on.
If you want the full capacity of a Junkers Bosch Gas Heater which is typically 11 litres a minute, then the ShowerPowerBooster will not this as its optimum output is 6 to 8 litres a minute.
If we made the ShowerPowerBooster bigger it would give 11 litres a minute but it would risk depressurising the incomming water main and it would cavitate. It would also be illegal to fit it on the incoming water main so I would not sell it to you.
A ShowerPowerBooster single or double boost will never depressurise a water main and a SPB will never capitate. It is the ideal and a legal solution to solving pressure problems in pipes feeding a Junkers Bosch water heater and indeed any other small instantaneous water heater.
As to what ShowerPowerBooster or pairing of ShowerPowerBooster to use I would recommend the SP21S double boost for automatic on off functionality, or the cheaper SP11S for manually switching on and off.
Outside the UK and Southern Ireland it may be prudent to buy two 22mm to 3/4inch conversion connectors:-
22mm to 3/4 inch conversion connectors