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Today had to fit new valves on radiators of a vented system. Drained system, pain as there wasn't a low level drain off valve. Fitted new valves, including a drain off. When I went to turn on the water at the F&E tank I noticed it still had water above the outlet pipe. Thought 'this could be trouble', F&E tank filled but system didn't. Thought that the outlet pipe was blocked, it goes straight down to the air separator but has 2 x 90 bends before it enters it.
First tried shoving a piece of wire down it, no difference. then tried filling from mains through new drain off, partially filled system hoping it would blow through outlet pipe to clear blockage, however only came out through vent pipe in to F&E tank. Vent pipe goes straight up from air separator to above F&E tank. Below air separator is pump and 3 way valve, and next to them hot water tank. Opened bleed valve on pump, dry. Above top feed to hot water tank is a bleed screw, dry. Lashed up a pipe from inlet mains with a hose and tried forcing mains water down the outlet pipe, it did not appear to make any difference.
I am fairly confident it is the outlet pipe from the F&E tank that has a blockage, probably at the 90 deg bends. It is an old system that has not had anything done to it for quite a while, hard water as well. Going back tomorrow to remove outlet pipe and check for blockages, is there anything else I can check.

Thanks for any relies.
 
Hi Mick sounds like a fair assumption of the situation. Corrosion and scaling on heating systems is always found on cold feed if anywhere, as the expansion, contraction and evaperation exposes this section of the system to new water, allbe it in small doses.
 
guy at baxi told me to always use compression fittings for connecting feed into heating for easy removal to clean or replace, also said should always tee feed into heating from underneath cant remember why though lol
 
guy at baxi told me to always use compression fittings for connecting feed into heating for easy removal to clean or replace, also said should always tee feed into heating from underneath cant remember why though lol

Mikegas, I have found feed teed from underneath worse, seems to block on the elbows. suppose any crud in system drops in and can't get out

Eco
 
Thanks for the replies. Still on going but I think there is progress. I did not switch the 3 way to man when emptying but I tried when filling, unfortunately I cannot see the selector on the valve because of where it is situated so only went by feel and moved to what I thought was manual position. In the cupboard with the hot water tank the flow pipe enters from below and then goes up to the air separator, there is a vent pipe from the sir separator to the F&E tank above. The flow pipe exits the air separator and just after here there is a 'T' where the cold feed to the F&E tank enters. I have removed this pipe and checked it and it is clear. The flow pipe then goes to the pump and then to the 3 way valve. Prior to draining down the system the heating was working fine so the water must have been passing through this section without problems, the only part coming in to it is the cold feed and that is clear. I am going back tomorrow, is there anywhere that there could be a big airlock that I have missed?
 
I did not switch the 3 way to man when emptying but I tried when filling, unfortunately I cannot see the selector on the valve because of where it is situated so only went by feel and moved to what I thought was manual position.
A small mirror is helpful in these situations.

Turn the power off to the system and the valve will move to the Auto position. When you move it to Man, there will be some resistance as you are opening the valve against a spring. The lever can be locked in the Man position in different ways, depending on valve make: a notch, push lever in or pull lever out.
 
yes I would put money on it being an air lock, I had this problem before where I could not get the downstairs rads hot, I did the usual things like blasting the mains through until the tank overflows with the vent pipe capped etc, this job was a bloody nightmare as I only went to put a new rad in,It started to work intermittently and eventually cured itself thank God, You will get there eventually and the next ones will be a piece of cake,good luck
 
Went back this morning and pulsed mains water up the vent pipe which is connected to the air separator. Lots of crud came out and eventually the system started filling. Bled all the radiators and the pump and everything was set to go. Turned on heating and pump started and water was moving around the system, however the boiler did not fire. When I first filled the system with a hose connected to the drain valve I turned on the boiler to try and get movement around the system, at this stage it fired up okay. When I checked the pump (which is near the top of the system by the hot water tank) found there was not enough water to fill the pump and so no water was being pumped around the system, there was water in the boiler and all the pipework leading to it. I turned off boiler at this stage.
I checked to see if there were any reset buttons or something that could have tripped but could not find anything, I am not a gas engineer so cannot do anything else. The boiler is a British Gas F2, looks quite old but in good condition. I advised the client they would have to get a boiler engineer to have a look at it.
 
i suspect it is an ideal classic and it will have a reset button once you drop the cover down ,it will be brownish colour with a circle and a cross in the middle , just call the customer and see if they have the instructions for the boiler I am sure they will be grateful for your perseverance
 
Thanks Gasmarc, however there is no flap on the front. Did more searching on the internet and found it is a potterton profile, the reset button is in a hole underneath it. I had looked underneath but did not notice it. Sent a message to the customer and he reset the boiler and all is okay, he has had his first hot bath in 3 days and is well happy.
 
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