First up: I am a newbie, so bear with anything that might seem obvious or simple please. We have a 2-zone, hydronics baseboard heater system. About a year ago my Great Dane mix chewed through the copper piping and aluminum fins in the LR heater (quite the mess). I had a plumber come out and repair the pipes - he removed the damaged pieces and soldered in new ones. Before he left he cranked up the heat and it did come on. All seemed well... But, this past winter has been COLD on the first floor. Upstairs, the heat is fine, but it almost never comes on downstairs now. I have replaced the thermostat, but this didn't solve it. Based on my reading this forum, I am guessing I have air in the system. I have a 1-page little sheet titled "Instructions for Installing Watts Feed Water Pressure Regulators Series 1156F, T156B and N256". I think I am supposed to open one of these levers and let out the air, but I am nervous and unsure which one. What do I look for? Do I need to drain water? Could I hurt myself? Should I post some pix to give a clearer idea of this problem? Any help would be appreciated. Thanks

Last night I asked my friend to flick the switch for the immersion heater so we could both have a shower before we went out. I got home to find she'd actually turned the water off and not the immersion on! (the 2 switches are next to each other) So I stuck the water back on last night, left it til this morning and it was still cold. Then I stuck the immersion on allllll day and 12 hours later its still stone cold, what could it be? Its electric economy 7 if that makes any difference?