Reverse circulation on central heating

[smmjh11]

Hi

I have a Potterton Suprima boiler and an unvented system with a Megaflo hot water cylinder. I have just turned on the central heating and have noticed that I am getting reverse circulation. I cannot say I noticed having reverse circulation when we first moved in the house in March so I am assuming it has started after being switched off for a few months. I have 2 Danfoss motorised valves, one for the upstairs radiators and one for the downstairs radiators with separate room stats and also most rads have TRV's and a Honeywell motorised valve which I believe is for the hot water as it is near the primary flow on the Megaflo cylinder. The pipework is small bore compared to the 15mm piping we had in our old house. Also their is a red expansion tank with a pressure guage which I assume is for the pressurising of the central heating system. What could be the cause of the reverse circulation. I am just getting my head around how the megaflo cylinder works. Oh to have a basic system similar to what I had at my old house.

thank you in advance

mark

 

[TCCHeating]

The hot water return from the cylinder should be the last connection into the boiler return pipe before it gets to the boiler. Google the three tee rule for more info. If the piping is correct suspect motorised valve is passing

 

[smmjh11]

I have taken the heads off the two motorised valves for the upstairs and downstairs radiators and they seem to be working OK when the room stat is switched on and off. Will a motorised valve passing just heat up the radiators a little as all my radiators are getting hot as the heat is coming through the return pipe and then returning via the flow pipe(where the TVR's are connected)

 

[TCCHeating]

I Just reread your original post and im a bit confused to why you suspect reverse circulation? This is normally when the rads are getting hot when the hot water is on, so you would have noticed this regardless of if you had the heating on. Most newer trv's are bi directional so it doesnt matter if they are on the flow or return. Does your system work as it should? Im still not too clear if you have an actual problem or if you you are worrîed the trv's are not on the raduatior flow pipes

 

[smmjh11]

TCC

I think you are correct. I thought that because the water was flowing through what I thought was the return pipe it was classed as reverse circulation. Must admit when we first moved in I did not notice what side of the radiator was getting hot first so just assumed it would be the same as our old house.

Thank you for taking the time to explain.

Mark