No heating, but switch works

I have a boilermate 2000 coupled with a Ideal FF370 boiler and a Siemens RCR10/433-GB wireless thermostat.

Hot water is being delivered and the boiler is firing at times, however we can't get any central heating unless the 'switch' is used.

I've run through the Sw1 / Sw2 checks and get the following readings.

Store_T1 41 T1_ON 74 T1_OFF 77
PHE_T2 36
DHW_T3 34

When I turn the room thermostat up, Bar 1 on the LED display for HT lights up.

The pump that is connected inline to the pipe marked in the manual as item D Primary Return (to boiler) is very hot but the pipes either side are hand touchable warm.

Any help / suggestions appreciated.

Martyn,

The warm pipes but high temperature of the pump itself strongly suggests the pump is jammed. You can free it by taking the big silver screw out and spinning the motor shaft with a screwdriver. Video here showing how:
https://www.youtube.com/watch?v=F5sMNa8bjrA

Hi Mike

I've tried that on all 3 pumps, all 3 rotated freely and the problem still persists.

Hi Martyn
If you see my over post today you will that there is a potential problem with blockages within the flexible flow and return pipes in the boilermate thermal store. I plan to drain down the system and either remove the push fit connectors or leave the push fit connectors in place and open the compression fittings either side of the push fit connectors. It depends on how easy the flexible push fit connectors will remove from the copper pipe. I wonder if anyone else has tried to remove the push fit connectors?

You may have already tried this but if you hold a screwdriver or similar on the boiler circulation pump and other end against your ear can you hear the pump running?

Thanks for the reply. I had not tried that one before but is a good way to test it is working. The circulation pump is working after just testing it with your method. This pump was changed around 12 months ago. The gas boiler linked to the Thermal store locks out before Thermal store can reach a temp of 60C and was informed by a heating engineer /Gledhill that is a circulation issue due to sludge. As the temp can’t reach 60C the central won’t come on so this leads me to believe that it’s the Thermal store with the issue and not any specific radiator. I can’t test the heating pump as will not operate until store reaches 60C. If the flexi hose linked to the pump is full of sludge then maybe this is why the gas boiler can’t keep up with the Thermal store and so locks out. When I drain the system down I could potentially open up the circulation pump and stick a tube or something through the pump down into the Flexi hose to see if there is any restriction in the Flexi hose or copper pipe . If all seems ok then would be no point in me remove the Flexi hose. The heating engineer also checked the Thernister and overheat stat in the Suprima 50 gas boiler. Heating engineer also suggested a powerflush but u are not meant to powerflush the boiler mate only the radiators. Sorry for the lengthy reply and thanks again for the pump tip.

It does seem as though circulation rate may well be the issue. The boiler should be set to run at max temp and the circulation pump set on fastest speed I understand. If you have a suitable thermometer (cooking one works) you can check the flow and return from the boiler you would want to see high 70 s on flow and somewhat lower on the return of course, as some heat will be shed to the heatstore. Someone had similar issues and it turned out to be the pump gunged up. Others have seen blocked isolation valves that sort of thing Good luck

Thanks for the thermometer tip. I have always run gas boiler on max and pump on fastest speed. The gas boiler locks out quickly if on max temperature. If gas boiler on very low can sometimes run for an hour before lockout. Unfortunately having the gas boiler on low is not enough to get thermal store upto 60C to operate central heating. It is enough to provide hot water. At plumbers merchants today they don’t think it would be the Flexi hose but more likely the pump like you said. Thanks for the advice, much appreciated and hope you sorted your issue out.

mmartin wrote:You may have already tried this but if you hold a screwdriver or similar on the boiler circulation pump and other end against your ear can you hear the pump running?

Yes had tried that, there was 240v to the terminals on the pump but it was not spinning at all despite being free.
Took the bleed screw out of the pumpt and put an electric screwdriver in reverse onto the pump shaft and made it spin which got the water flowing back into the BM and the store temp crept up to 60 after which the heating pump kicked in and we had heating.

So the pump is getting swapped out right now as I type this, well after the tank has finished draining first.

Great work hope new pump sorts it for you. If draining system to change pump and not using isolation gate valve would be good to check Flexi push fit pipes below pump in case there is any restriction in the pipe with sludge . On another thread the flexi pipe supposedly only had 2mm gap left!

Matey wrote:Great work hope new pump sorts it for you. If draining system to change pump and not using isolation gate valve would be good to check Flexi push fit pipes below pump in case there is any restriction in the pipe with sludge .  On another thread the flexi pipe supposedly only had 2mm gap left!

They're putting new valves above / below the pump too so will ask. Thanks for pointer.

Sorry to bother you again. Hope all went ok with pump installation. When my circulation pump was changed 12 months ago the isolation valves either side of pump were not changed and maybe this could be the problem. Was there any sludge in the valves or in the Flexi hose below the pump?

I decided to check the Flexi hoses within the Boilermate 2000 due to Potterton boiler locking out and the low temperature readings on the flow and return pipes within the Boilermate Thermal Store. A heating engineer said I needed a new system due to sludge after checking the Thermistor and overheat stat in the Potterton boiler.

I drained the system and removed the Flexi hoses by undoing the compression fittings either side of the Flexi hoses. Don’t think it was possible to pull off the Flexi hoses and reuse.

My gut feeling was correct as the Flexi hoses were completely blocked with sludge which was like concrete! When I ran the Flexi hose under the tap only a drip of water came out the other end. I had to hold the Flexi hoses with a wrench and pour boiling water into it and used a metal rod to break down the sludge. The bore within the Flexi hoses is only around 10mm compared with the 22mm copper pipe. Be prepared for black sludge to pour out of the Flexi hose on removal!

I was informed by a reliable source that the rubber inside the Flexi braided hoses is pourous which allows oxygen into the system which promotes sludge. The Flexi hoses are also prone to collapsing.

After refitting the Flexi hoses the boiler now works and have put cleaner and inhibitor into the system.

The draining process was very time consuming as only the first floor with boilermate drained from lowest radiator on the ground floor. I had to individually drain the other 6 radiators on 3 occasions to remove the cleaner from the system and to get water clearer. I did at one stage have 4 hoses attached to 4 radiators on the ground floor to flush them out a bit better. However 2 of the radiators still had a significant amount of water in still which nearly caught me out!!

Don’t forget to clean out the Feed and Expansion tank in the loft before draining otherwise all the crud at bottom of the F&E tank will enter the thermal store. I used a clear 12.5mm hose to clean tank by putting one end securely in the toilet and once water built up from water in the tank gravity took over . All I had to do was move the hose inside the tank to suck up the crud at the bottom. Don’t let hose come out of water otherwise you will have to start again!

Before putting inhibitor in the system I got a local heating and plumbing engineer to remove the Flexi hoses and change to copper pipe.

If ever your boiler locks out, check your flow and return pipe temperature in the Boilermate thermal store as the Flexi hoses maybe blocked. My system is 18 years old so not sure how much life is left in the system. Fingers crossed as all radiators now balanced and radiating a lot of heat!

I never want to bleed 19 radiators again!

Very thorough well done. A tip is turn off all the radiators when draining then you don't have to wait for the water in each one to trickle out. Obviously remember to open them all up when sealed up and ready to refill. Regards Murray

Thank you, it feels good when the hard work pays off!