Adding central heating controls. Is this right way to go?

[Clive M]

current heating is gravity HW and pumped heating - All rads except bathroom have TRV, and none of the rads are balanced.

There is no tank or room stats at all. A 7day timer is fitted

Current plan (based on improvement gained / ease of installation) is:

a) Leave system as Gravity HW / Add 2 port valve close to boiler to give independant control the HW. b) Leave curent timer on system, and set to control control time for HW - heating always on c) Add a Danfoss wireless cylinder thermostat to control HW temp (wireless as wireing between cylinder and boiler would be complex) d) Add a Danfoss TP7000 Room stat to Hall (Lock existing TRV to full on) e) Balance all rads (i.e 12deg temp differential)

Am I missing something in my thinking, before I order the parts?

[Christian McArdle]

1. You may need something to prevent gravity circulation in the CH circuit. This will depend on circumstances, but could be either a 2 port valve or a one way valve (with circuit flow set to be against natural convection). It may not be necessary.
2. Remove the TRV from the roomstat room. Some well meaning person WILL turn it down.
3. Ensure boiler is safe with valve on the gravity circuit. It may need that circuit to be free flowing for two reasons. Firstly, it may need somewhere to dump heat at all times (particularly solid fuel boilers). Secondly, it may need the circuit to provide a steam outlet/quenching water inlet path. This would either require careful layout to ensure that the 2 port valve doesn't block those paths or require the boiler to have an overtemperature safety cutout and pressure relief valve.
4. Consider pumping the hot water gravity circuit.

Christian.

[Mark]

Why would you need something in the circuit to prevent gravity circulation in the CH circuit, if control is added to the HW circuit. I presume that at the moment, when HW only is running there is already no circulation in the system? The current system will already be HW only or HW & CH. With a 2 port valve you get the options of HW Only / CH Only / HW & CH

Agreed - but would work in the short term. Some TRV can be locked off to prevent them turning.

[G&M]

Never met one in a hotel that couldn't be persauded to give a little more heat in winter.