converting to fully pumped system

[taydo]

Hello

I am about to price to convert a semi pumped system, gravity fed to the cylinder to a fully pumped.

As you probably know I am new to heating, so please correct me if I am wrong.

Cut off and cap gravity fed side of boiler reconnect cut ends to pumped side via a controls pack.

Is that it? are there any obvious problems that may be encountered.

What type of control pack do you recommend for this type of job Y or S
plan.

Thankyou

Brian

 

[oilman]

I converted an old (50 yrs) gravity system (ALL gravity, no pump at all). I used an S plan as I saw it as less long term trouble than a Y plan The system has 35mm pipes in many places. Biggest problem is where the existing pump is on the return side of the boiler. Where is your's?

 

[taydo]

its on the flow.

if it was on the return why does that make it a problem as long as its running ok already

 

[oilman]

I did work it out, and managed to forget the details. It's to do with the pressures when the system is running. If its on the return, and you shift it to the flow the pressure in the boiler goes down, I really can't recall the details now, but sometimes it is difficult to get the system to work properly.

 

[ChrisR]

You will have to decide where the feed and vent pipes go. Chances are they'r in unsuitable places now.
Also you'll need an automatic bypass you don't have now. It has alll been described on the forum, but to be honest you'd be better off with a few pictures and explanations from a library book.

So in short - no it isn't that simple.


If you put your pump before the boiler, ie on the retun, think about the pressures in the system. The vent will be just after the boiler, ie first inthe flow pipe. That will have a head of water in it, typically about 3 meters. The pump will start wth a head of 5, 6 or more metres. That means that some of the pipework before the pump has negative pressure. What that means is that you'll suck air in tiny leaks which will corrode your rads.

 

[taydo]

Thanks

for you help again

By what I can gather as there is already a pump on the system and its working ok I should be fine,
if the pump was on the return or there was no pump at all then it can become a problem.

Oh well here it goes sink or swim I can always change it back