Cold radiators downstairs problem

[matot]

Good morning guys, I have problem with cold radiators downstairs and very hot water in cylinder.
I just fitted new pump ( Grundfos UPS 2 15-60 6m Head).


If I set pump to I. speed, Radiators (R3, R4, R5) on first floor get hot but not enough. Downstairs radiators (R1, R2) are cold. If I close vents on radiators upstairs, downstairs radiators get warm but just 25°C - 30°C in one hour of time. Gravity return (GR) pipe from hot water cylinder is nearly same hot as gravity flow (GF) pipe when I touch it close to back boiler (point D)


If I set pump to II. speed and open radiators upstairs, downstairs radiators still cold and water will start drops from pipe out of house (point C).


If I set pump to III. speed both pipes to expansion tank (green pipes) get hot and water is leaking from pipe out of house.


Please have a look on this scheme of my heating :


I thing problem is pump fitted on pumped return (PR) pipe instead of Pumped flow (PF) pipe. So pump is pumping water in to boiler (Baxi Bermuda 552) and increase pressure inside boiler to pumped flow pipe but also in to gravity flow (GF) pipe. For water is easier way to flow to cylinder and back to boiler (22mm pipes) than to radiators (15mm pipes starts on firs floor)

I cant fit pump to PF pipe, there is no space for pump.

I want to ask you guys if is it good idea to fit single check valve on to gravity return pipe (point D) to stop water go this way in to cylinder and to fit gate valve on to gravity flow pipe (point E) to decrease flow in to cylinder.

Thank you very much for any help.

 

[PrenticeBoyofDerry]

firstly have you checked the system for sludge or blockages and are the radiator valves operating correctly?

 

[45yearsagasman]

Fitting valves where you propose is a very bad idea. Your system looks to be piped up correctly, if a little old fashioned. As suggested above, do those checks. With such a small system your pump should not need to be set to 111. It may also be the distributor tube inside the boiler has failed in some way. do all the basic checks first. Why was a new pump required?

 

[matot]

firstly have you checked the system for sludge or blockages and are the radiator valves operating correctly?

All radiators have fitted new valves and they are all opened.
I flushed downstairs radiators with garden hose last weekend. They wasnt blocked and I think it flushed out all sludge from them but it didnt help at all. This weekend I am going to remove and flush all upstairs radiators.

 

[matot]

Fitting valves where you propose is a very bad idea. Your system looks to be piped up correctly, if a little old fashioned. As suggested above, do those checks. With such a small system your pump should not need to be set to 111. It may also be the distributor tube inside the boiler has failed in some way. do all the basic checks first. Why was a new pump required?

How can I chech distributor tube please?
It is back boiler fitted at bottom of chimney. Only way to be remove wole boiler probably.
Old pump replaced due to body of pump was getting hotter than water in pipes. And sometimes didn't spin without help.
Thanks.

 

[Agile]

Your system probably needs balancing properly. See FAQ.

Check F&E tank for the correct level and pipe clearance dimensions.

These systems are very simple but largely unsuitable for DIY work that alters their operating parameters.

With an uncontrolled gravity hot water system like that the hot water will get to the boiler flow temperature which can be dangerously too hot. Turning down the boiler control knob will of course lower it but at the expense of rad temps.

It would be best to change it to a fully pumped system.

The boiler while very reliable needs annual servicing and is very inefficient by modern standards.

Tony

 

[PrenticeBoyofDerry]

Even if bottom rads had been given a good flush out, if above ones have not all the sludge left in system will still drop to lower rads.
Was there plenty of sludge visible when cleaned them?

 

[matot]

Even if bottom rads had been given a good flush out, if above ones have not all the sludge left in system will still drop to lower rads.
Was there plenty of sludge visible when cleaned them?

I was able to see trough valves opens, so not completely blocked. Black water was coming out over 1 minute when conected to garden hose.

 

[matot]

Flushed all radiators and also boiler. Boiler wasnt blocked some black water but not a lot. Only one radiator upstairs working now.
Tried to set pump to speed III and switch Off and ON few times to get rid of air. Didnt help.
There must be airlocks.