Heating Conundrums (part two)

Part two (really it's part 4 or 5, if we count all the things we've done to try to fix our heating system since we moved here - but it's part 2 for this round) was a little bit of an upgrade and a little bit of an experiment. First though, back to where we left off - with a new foot or two of pipe. Unfortunately, when we filled the system with water again, it dripped a little. A slow leak, like a droplet or two every minute. But still enough to make us nervous. So we yet again bled some water out of the system and prepared to do battle.

Reducing the pressure in the system gave us the flexibility to make some tweaks to it. D replaced all the old, rusty valves after realizing that it was fairly easy to do and made for a much easier time bleeding the system. So, for example, the valve in our upstairs bathroom went from this:

To this:

(None of this is very visible when the covers are in place.)

Then we called in a plumber/heating repair guy to come and have a look. After checking over the whole system, he noticed this pump--which he said looked like it was added to the system after it was built. He figured out it was the loop to our master bedroom. He suggested that we try turning it off (there's a simple on/off lever at the top) and seeing what that would do. It would be something easy to try and yet another diagnostic to try to get to the bottom of our heating woes. He said that he would come back and fix our leak, as well as try to fix the whole system, once we gave this a try on our own. And then, after spending about a half hour at our house offering helpful suggestions, left without charging us.

We tentatively pressurized and ran the system (with a bucket in place below the leaky pipe). Lo and behold, we had heat to the whole house! Well, almost the whole house. We had heat everywhere but the master bedroom.

After reveling in the fact that the baseboards in the guest bedroom, office, and main bathroom were actually hot to the touch for the first time EVER, we headed up to the bedroom to try to sort out what was going on. D rigged a hose to the valve and bled the system out the window, hoping to unclog a few air bubbles.  To no avail. After a while, it got too hot in the rest of the house to keep experimenting, so we turned the heat back off.

We think what is happening is that previous owners probably got no heat to that one bedroom and had someone come in to fix the problem. That repair guy installed a pump to divert extra hot water from the main circuit up to the master bedroom. The problem is that it may be pulling too much hot water and not leaving enough for the rest of the house.

Needless to say, we aren't willing to compromise on either having heat in our bedroom or in bathroom/office/guest room - so we still aren't quite at a solution. But we might be getting warmer...(I couldn't resist!)