Hello everyone.
I have an ageing central heating system that still works fine and outputs plenty heat however it bangs loudly from the boiler area when switching off due to possible build up of sludge.
The symptom is as follows...
I have gravity hot water and pumped central heating with an injector tee for the water circuit. When the heating is on and the thermostat is calling for heat everything is fine. When the room thermostat is satisfied the power to the pump is cut however the boiler remains lit, as it's supposed to, to continue heating the gravity hot water. This results in very loud banging if the boiler stat is set to anything other than LOW as a result of the water not escaping the heat exchanger fast enough.
What I did to try and combat this was to also wire the boiler to the room stat so when the room stat is satisfied the pump AND boiler turn off. This is working great if I keep the boiler at LOW or just above however this means the rads only heat to approx. 46 deg. This wiring setup is ok for winter when the heating will be on long enough per day to ensure the hot water tank remains hot. During summer months I will revert wiring so hot water ONLY can be selected.
The solution I have thought of is to include some sort of time delay realy for the pump power supply
1. room stat will switch off once ideal temperature is reached
2. power to boiler is instantly cut extinguishing flame
3. time delay will kick in (approx. 5-8 seconds)
4. after time delay pump will switch off
As a result of the above what will happen is I can have the boiler set to 70 deg for rads and when the boiler is off and the pump continues for the 5 or so seconds this will be sufficient in drawing enough heat from the boiler therefor no loud banging from pipework.
I can do this manually by turning boiler stat to 0, wait 5 seconds then turn down room stat to turn off pump = no banging so the time delay relay will automate this all for me.
What I think I need is a time delay relay that starts the power off count down when a voltage is removed ie the power supply to the pump that the room stat cuts.
If anyone can recommend a particular switch and possibly supply a link that would be appreciated.
The alternative to all this is to convert various rad valves and get a power flush at many hundred pounds so am willing to try this electrical solution first.
PS the boiler is an 18 year old cast iron baxi Bermuda inset 2 50/4 (power requirement 4 watt!)
Many thanks and sorry for the long ramble!
Steve
I have an ageing central heating system that still works fine and outputs plenty heat however it bangs loudly from the boiler area when switching off due to possible build up of sludge.
The symptom is as follows...
I have gravity hot water and pumped central heating with an injector tee for the water circuit. When the heating is on and the thermostat is calling for heat everything is fine. When the room thermostat is satisfied the power to the pump is cut however the boiler remains lit, as it's supposed to, to continue heating the gravity hot water. This results in very loud banging if the boiler stat is set to anything other than LOW as a result of the water not escaping the heat exchanger fast enough.
What I did to try and combat this was to also wire the boiler to the room stat so when the room stat is satisfied the pump AND boiler turn off. This is working great if I keep the boiler at LOW or just above however this means the rads only heat to approx. 46 deg. This wiring setup is ok for winter when the heating will be on long enough per day to ensure the hot water tank remains hot. During summer months I will revert wiring so hot water ONLY can be selected.
The solution I have thought of is to include some sort of time delay realy for the pump power supply
1. room stat will switch off once ideal temperature is reached
2. power to boiler is instantly cut extinguishing flame
3. time delay will kick in (approx. 5-8 seconds)
4. after time delay pump will switch off
As a result of the above what will happen is I can have the boiler set to 70 deg for rads and when the boiler is off and the pump continues for the 5 or so seconds this will be sufficient in drawing enough heat from the boiler therefor no loud banging from pipework.
I can do this manually by turning boiler stat to 0, wait 5 seconds then turn down room stat to turn off pump = no banging so the time delay relay will automate this all for me.
What I think I need is a time delay relay that starts the power off count down when a voltage is removed ie the power supply to the pump that the room stat cuts.
If anyone can recommend a particular switch and possibly supply a link that would be appreciated.
The alternative to all this is to convert various rad valves and get a power flush at many hundred pounds so am willing to try this electrical solution first.
PS the boiler is an 18 year old cast iron baxi Bermuda inset 2 50/4 (power requirement 4 watt!)
Many thanks and sorry for the long ramble!
Steve