Remote thermostat connection to boiler
Posted: Wed Oct 03, 2012 2:17 pm
I have recently had a new boiler installed and I now want to update the control system. The new system requires the thermostat on the hot water cylinder to be connected directly to the boiler. It's a standard mechanical thermostat with three connections.
The problem is that the hot water cylinder is on the first floor and the boiler on the ground, but not directly underneath; there is no simple way of running a cable between the two. The obvious answer is a wireless solution. I have looked at the wireless cylinder thermostats available and they would do the job - but at a very high price (approx £100). The obvious solution is to build something myself. The problem is that my electronics knowledge stops at transistors - I used to be able to design and build an amplifier - ICs are a dark art.
The attached block diagram shows what I want to achieve.
My thoughts are as follows:
1. The transmitter only needs to transmit when there is a change of state;
2. When the thermostat closes, the transmitter will send a signal which closes the relay, which should then latch in the closed state.
3. When the thermostat opens the transmitter will send a signal to unlatch the relay.
4. I think transceivers may be required at both ends to ensure that the signal from the transmitter have been correctly received.
5. Some form of encoding would probably be required, e.g Keeloq, to ensure it does not interfere with other electronic devices on the heating system.
5. I realize that the devices will need low voltage DC to power them, but I would prefer this to come from the mains, not from batteries. Router type power supplies would be acceptable, but I would prefer the power supply to be built in.
6. Transmission distance will be about 30ft, through a floor and one wall.
Finally, I would love to build the devices rather than buy them off the shelf - not that I can find anything remotely suitable.
So, if any kind reader can provide a circuit diagram and list of components, I will have a go.
I
The problem is that the hot water cylinder is on the first floor and the boiler on the ground, but not directly underneath; there is no simple way of running a cable between the two. The obvious answer is a wireless solution. I have looked at the wireless cylinder thermostats available and they would do the job - but at a very high price (approx £100). The obvious solution is to build something myself. The problem is that my electronics knowledge stops at transistors - I used to be able to design and build an amplifier - ICs are a dark art.
The attached block diagram shows what I want to achieve.
- Remote thermostat block diagram
- Remote thermostat.JPG (13.65 KiB) Viewed 2750 times
1. The transmitter only needs to transmit when there is a change of state;
2. When the thermostat closes, the transmitter will send a signal which closes the relay, which should then latch in the closed state.
3. When the thermostat opens the transmitter will send a signal to unlatch the relay.
4. I think transceivers may be required at both ends to ensure that the signal from the transmitter have been correctly received.
5. Some form of encoding would probably be required, e.g Keeloq, to ensure it does not interfere with other electronic devices on the heating system.
5. I realize that the devices will need low voltage DC to power them, but I would prefer this to come from the mains, not from batteries. Router type power supplies would be acceptable, but I would prefer the power supply to be built in.
6. Transmission distance will be about 30ft, through a floor and one wall.
Finally, I would love to build the devices rather than buy them off the shelf - not that I can find anything remotely suitable.
So, if any kind reader can provide a circuit diagram and list of components, I will have a go.
I