Booster pump installed successfully, but now boiler goes to overheat!

[Vitali]

Hi all, need advice as I am an amateur who wanted to improve things but made it worse. Ok, have a duplex apartment with a Baxi solo 2 gas central heating. All working ok but the gravity fed shower upstairs was slow in water pressure, and I found this cheap 0.9 Bar electric booster pump on Amazon and spent half a day installing it myself and to my surprise had no leaks and when switched on it did the job as described--- water pressure increased to have a good quality shower. I installed it on a hot water feed going from hot water tank to shower. When happy with myself I switched the boiler to heat up the water, it started as usual but in 2 min cut off and overheat light came up. First I decided to reset the PCB, so I switched it off for 10 sec. The pipe going out of the boiler was really hot, so just in case I let things cool down and came back to the boiler in 20 min. Started it, it did kick in and then again in 2 min stopped and showed overheat again. So, lads, what it is-- an airlock in the system or is that my pump restricting the water circulation and what do I do? I plan to go all the way back to where I started from disconnecting the pump as we all need a Good shower now. And I only hope it will be the same as it was before.... Thanks in advance!

 

[Amateur]

You say "All the rads are switched off now", you should always have 1 open. Someone with more knowledge than myself will be better to explain why. Could this be your problem?

 

[Darren Jackson]

One of the gate valves on the coil or pump could very easily have broken they often do! you think it is all turned on but one could have stayed jammed shut. try loosening the nut & olive on the valve on the side of the pipe that is not getting hot to check if it has opened up properly.

 

[Vitali]

Hi again, did what you told me, took out the valve going to the bottom of the cylinder, (in the picture red top on), first the water shoot out of the coil/cylinder about 3 litres, stopped. Then when I opened the valve another 2 litres came out and then stopped. I thought it should be always under pressure??? Took me the valve completely-- perfectly working valve. Sucked some water/air from the cylinder and the pipe just in case. Put it back. Climbed to the attic and did the same with the vent pipe-- sucked out the water. Went back to the boiler, switched it on, started good as usual after 2 min work- off to overheat again, plus some crazy noises in the pipes this time. Circulation pump hot and working. Completely lost. Time for a professional to clarify things as you all suggest...

 

[Amateur]

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[jajodu]

When you loosened the red gate valve you essentially drained most of the water from the boiler circuit, go to your boiler and check the pressure guage, what does it show? If it's showing empty then use the filling loop to top it up to 1.0 - 1.5 bar. Then try again.

 

[Darren Jackson]

Marc K, why the dislike? I was only trying to offer some friendly advice!

 

[Vitali]

Hi people, I guessed it was something simple and it was... The valve just before the circulation pump got stuck and hot water from the boiler would not get into the pump. It was less then half open and would not open fully. The other valve straight after the pump was not in the best condition. It took a good bit effort using the "convincer"/hammer to disconnect the pump and replace both valves and it's all perfect now.
Thanks to all your suggestions and advice!

 

[Darren Jackson]

Glad you got it sorted mate, and also pleased I was correct that the gate valves had not opened back up correctly. Still don't know why I got the dislike for suggesting it though from Marc K? Funny old world!

 

[Vitali]

Yes, Darren, you were right, because I am an amateur I didn't know that was a gate valve by the pump (the one with a small screw-like shutter you open/close with a flat end screwdriver. I genuinely thought it was air release valve and twisted it myself, noticed a small leak and tried to screw it back but it wasn't going back fully. When the plumber disconnected it altogether I saw that it was a gate valve full of black burn inside. Anyway, my silly mistake, shouldn't have touched it. Don't worry about the dislike, I will balance it out now by liking your comment . Thanks!