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Stu123

Hi,

My dad and I put a pump in the down tube from the hot water tank down to the boiler to speed up the flow which was just convection before. The pump is down by the boiler.

What we cannot understand is why the pipe that the pump is on heats up so quickly when the pump is switched on (when thermostat is on and boiler is in hot water mode), but the pipe out of the tank stay stone cold and only gets luke warm after a while. We obviously checked the dirention of the pump and that it is rotating in the right direction, but we are perplexed.

Can any experts shed any light on this for us? Thanks for any help

Stu
 
Am i correct in thinking you have put a pump on the 28 mm gravity circs to the cylinder to speed it up? So you had gravity HW and pumped CH?
 
Is cylinder getting hot,if so,you will be loosing heat to the cylinder,be carefull though you can not just put a pump on gravity pipework,you may also have to change pipework as pump may pump up and down vent pipe and cold feed through header tank,as often vent on cylinder feed and cold feed on return
 
Am i correct in thinking you have put a pump on the 28 mm gravity circs to the cylinder to speed it up? So you had gravity HW and pumped CH?

Hi, yes that's right

Is cylinder getting hot,if so,you will be loosing heat to the cylinder,be carefull though you can not just put a pump on gravity pipework,you may also have to change pipework as pump may pump up and down vent pipe and cold feed through header tank,as often vent on cylinder feed and cold feed on return

We put the pump down at the bottom of the cold return to the boiler, so it is about 20 foot below the header tank and vent pipes.
 
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You cannot simply fit a pump to a gravity system. The pipework must be modified and a suitable control system added in accordance to recognised practice.

You need what is called an "S plan" or "y plan". A search on google will provide lots if info.
 
You cannot simply fit a pump to a gravity system. The pipework must be modified and a suitable control system added in accordance to recognised practice.

You need what is called an "S plan" or "y plan". A search on google will provide lots if info.


Thanks for that. After some looking around, I see that we have a C system in place. However I can't find out what the dangers are of having put this pump in the system. The pump is only working when the HW cycle of boiler is on and the tank thermostat is on.

What mods do we have to make to the pipework, and what type of valve needs to be added.

Thanks for help
 
The pipe out of the cylinder will be cooler as the heat from the pipe that goes into the cylider is being tranfered to the cold water stored in the cylinder via the coil, as long as your getting a tank full of hot water after the boiler has been on its "hot water heating cycle" I cant see what your problem is?.
Convert as somone else has just said, to an S or Y plan you can buy a complete kit and you will be able convert it easily,soooooo much better and effective than the way youve done it. It will pay for itself in fuel savings alone.
 
The pipe out of the cylinder will be cooler as the heat from the pipe that goes into the cylider is being tranfered to the cold water stored in the cylinder via the coil, as long as your getting a tank full of hot water after the boiler has been on its "hot water heating cycle" I cant see what your problem is?.
Convert as somone else has just said, to an S or Y plan you can buy a complete kit and you will be able convert it easily,soooooo much better and effective than the way youve done it. It will pay for itself in fuel savings alone.

Thanks for the advice, I will look into this and I think we will convert to one of those two.
 
I would always reccomend the S plan over the Y plan as you have two separate zone valves.

You can also program the cylinder and room which will save you loads of money on fuel.
 
Big problem with pumping the primary pipe work is you may be pumping the water via the expansion tank which will lead to aerating the water which in term will cause excessive corrosion in your system, a proper fully pumped system has both cold feed & open vents entering the pipe work on the inlet side of the pump which should prevent pumping over or sucking air in. you may think everything is working OK until yours rads rust through in a short time.
Hope this helps, but would suggest you read up first before attempting something like this.
Martin
 
Pressure test your system for leaks, and if it's OK, convert to a sealed system and chuck away that tank in the loft! Problem solved.
 
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