What are the advantages of fitting an Auto Bypass Vlave in place of a Manual Bypass valve?
Advantages of ABV over Manual bypass Valve
- Thread starter Longclough
- Start date
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An auto bypass valve (if correctly set) will always maintain the correct flow rate across your boiler. A manual valve will not adjust itself to the flow requirements.
A manual ABV will ALWAYS bypass some of the flow to the return reducing effective boiler output and lengthening the heat up period.
It also reduces the pump presure and so reduced the flow rate to the radiators. This is particular relevant when some rads are some distance from the boiler.
Tony
It also reduces the pump presure and so reduced the flow rate to the radiators. This is particular relevant when some rads are some distance from the boiler.
Tony
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Thanks for your replies.
I would like to understand fully how my central heating system works. Would I be right in thinking that the more that a manual bypass is opened the more heat is added to the return circuit to the boiler. Would I be therefore right in assuming that the boiler would cycle more as the return to the boiler would get hotter quicker than if the heated water had travelled through the radiator or cylinder prior to returning to the boiler.
Does that make sense or is it an incorrect assumption.
I would like to understand fully how my central heating system works. Would I be right in thinking that the more that a manual bypass is opened the more heat is added to the return circuit to the boiler. Would I be therefore right in assuming that the boiler would cycle more as the return to the boiler would get hotter quicker than if the heated water had travelled through the radiator or cylinder prior to returning to the boiler.
Does that make sense or is it an incorrect assumption.
That is correct. The more you open the bypass is allowing heated water to flow back to the boiler, bypassing the rest of the system. This would trick the boiler into shutting down prematurely before the rads are up to temp and would cause cycling.
Spring loaded valve.
A typical heating pump produces a head of water pressure of about 1-5 m.
When most TRVs are open the working head might be say 2 m head. The ABV stays closed at this time!
When most of the TRVs are closed or closing the flow through the rads reduces and as a consequence the pump pressure rises to say 4m head.
The ABV might well be set to start to open at 4m head and allows some flow to be diverted directly to the boiler's return. Thus a minimum flow through the boiler is continued so that it can correctly control its flow temperature.
Tony
Tony
Thanks everyone for the info.
Agile essentially are you saying that the only time the bypass should be providing a minimum flow to the boiler is when all valves have closed down. Or should a flow be always present through the bypass. ie for the case of a ABV it should be set only to allow flow once all valves are closed (say during pump overrun).
Agile essentially are you saying that the only time the bypass should be providing a minimum flow to the boiler is when all valves have closed down. Or should a flow be always present through the bypass. ie for the case of a ABV it should be set only to allow flow once all valves are closed (say during pump overrun).
Agile thanks for your response.
What I want to know is will a manual bypass which is open only have a turn have any damaging effects on the system. Also would a boiler cycle more if a bypass was open more. I would assume more heat would be returned to the boiler return quicker.
Thanks for everyone's comments so far
What I want to know is will a manual bypass which is open only have a turn have any damaging effects on the system. Also would a boiler cycle more if a bypass was open more. I would assume more heat would be returned to the boiler return quicker.
Thanks for everyone's comments so far
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