I have received some help (from Ed and others) tuning my CH in the recent past. The set-up is: a Potterton Netaheat conventional boiler (its stat set to 3); a Honeywell CM907 programmable thermostat at the hall (driving the CH pump); TRVs everywhere but the hall rad; and a hot-water tank with an external thermostat attached to it (set to 70; doubt I am getting that).
The coldest room is my lounge. I struggle to get it to 19.5 in this weather and the heating has been on for over 12 hours (though the room stat has cut in hours ago). According to http://www.heatandplumb.com/acatalog/radCalcs.html I need ~10K BTUs. According to http://www.heatandplumb.com/acatalog/620mm_High_x_1000mm_Wide_Round_Top_Radiators.html I have approx 13,200 BTUs available from my two, similar, 25-yo rads in the lounge. The TRVs are full on, as are the other valves. When the heating is on, touching the top of the rads is possible but painful.
The target temp is 21 degrees (for the room stat and for the lounge). The hall radiator is tuned well down and the room stat took two+ hours to get there and cut out this morning. While building up heat, I noticed that the boiler was cutting out, but the pump kept going. Is this detrimental to the pump/boiler?
The options I see (bypassing for now the investigation of window insulation; this room has three open sides and 10 m2 of windows) are:
- Increase the boiler stat - Increase the pump rate (not sure if this will heat the lounge faster? - Increase the room stat setting and let the TRVs sort out the rooms already well heated. I am concerned about the effect of this on the pump, given the throttled hall radiator.
How would one start?