Gravity fed radiator..
- Thread starter ali68
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the term balance applies to a system of a number of rads. What you have is whats known in the trade as `heat leak` because the cylinder does not require all the heat from the boiler. its possible to update soild fuel boilers using moden controls and `normally open` zone valves
Hi matey.should a gravity fed rad be balanced? Not much to go on but assuming it is a heat leak and the only rad then no. Just leave it fully open. If however you are installing it into an existing one pipe system of rads then yes. people do tend to get in a mess with theese systems adding on rads as there is a set way in which the pipework must be installed in order for the rad to work. On a one pipe system the length of the bypass must be longer than the length of the radiator in order to create suffiecient hydralic resistance to force the water through the rad. Also the gravity or density based flow system depends upon the wieght difference. So usually the best systems use top and bottm tappings on the rads allowing the hot water to flow in at the top and the cooler to flow from the bottom. Swept tee pieces also help and on some systems you will find a pump located wherever usually an old magnetic inductance type green in appearance.P.S. If the rad doesnt work ,fit a valve in the bypass and balance it down to direct the flow through the rad. Then go around and sucessivly balance all the other rads.A well desgned one pipe system does not need a pump. Hope this helps
Sorry for the lack of info, It's on a new fire my parents have had installed with the optional boiler fitted. The radiator is Tee'd from the primary pipes.
Just now the radiator is open full bore (15mm) and heats up fine but the DHW takes a while to heat, we were wondering if we closed the return slightly if this would direct more of the heated water to the coil instead of the rad.
The instructions stated it could run 1 rad only, if wanted.
I know what I'm trying to say!! hope the above made some sense.
Cheers
Just now the radiator is open full bore (15mm) and heats up fine but the DHW takes a while to heat, we were wondering if we closed the return slightly if this would direct more of the heated water to the coil instead of the rad.
The instructions stated it could run 1 rad only, if wanted.
I know what I'm trying to say!! hope the above made some sense.
Cheers
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the rad is there to acept excees heat once the cylinder is hot. Is it a new cylinder Part L ,if so it could have a new style coil which arn't good on gravity. Try reducing the rad return .More to the point is the flow off the boiler almost as hot as where it go's into the cylinder & what temp is the return out of the cylinder.If ya rads drawing to much heat u may not be getting a good thermal syphon on the primary circulation pipework.Is there at any time a whooshig noise from the boiler.
The cylinder is probably not suited to gravity circulation as has been suggested.
As for the radiator, if it's been installed as a heat sink, then it shouldn't have any valves. end of story.
What size pipes have been installed for the primaries to the cylinder.
As for the radiator, if it's been installed as a heat sink, then it shouldn't have any valves. end of story.
What size pipes have been installed for the primaries to the cylinder.
Quite so, but it should have valves, for the reason I've already given.doitall said:
If you wish to contradict this without giving any new reasoning, then I won't be going to the trouble of posting just to register my disagreement - you'll just know that I disagree.
Most modern cylinders will work reasonable well on a gravity circuit even though they are designed for a pumped system.
The difference is the old type for gravity had a 28 mm coil whereas the pumped kind usually have 22 mm and a longer length.
I would be more interested in the routing of the pipework. It has to have the flow rising virtually vertically to the top coil connection to work well. The return is less critical but is best going vertically down.
Can you measure the temperatures of the top and bottom heating coil connections with the fire on and tell us how they compare.
Tony
The difference is the old type for gravity had a 28 mm coil whereas the pumped kind usually have 22 mm and a longer length.
I would be more interested in the routing of the pipework. It has to have the flow rising virtually vertically to the top coil connection to work well. The return is less critical but is best going vertically down.
Can you measure the temperatures of the top and bottom heating coil connections with the fire on and tell us how they compare.
Tony
Hey for you plumbers inc myself we dont know any of the detaills of this install but ive seen 22s work fine on gravity. The thing is as a rule of thumb you should only have horozontal runs no more than one third of the vertical rise. This usually ensures adequate circulation. Plus air could be a problem, ever had to crack the top nut of the coil to let the air out where the coil is not installed levell by the manuafacturer.? Matey also says its solid fuel unless ime mistaken and the primaries should have a pressure relief valve on em in case the feed and vent freezes, least I think thats the reason. In my expierience gravity primaries are old hat and anyone considering them should reconsider as reheat times are longer than the time it takes to cause a row with your missis when you have bathed first. 
P.S. dont care about the valve thing I wouldnt fit em.
P.S. dont care about the valve thing I wouldnt fit em.Oops opened a small can of worms here.
Try and answer what you have asked.
Primaries are 28mm and do rise up to the tank.
Lock shields on both inlent and outlet of rad.
No safetyvalve that I could see.
Can't give you the in and out temps just now, as the tiler and decorater have asked for the fire not to be lit until they are finished. Probably the weekend.
Will let you now the outcome after the weekend.
Cheers.
Try and answer what you have asked.
Primaries are 28mm and do rise up to the tank.
Lock shields on both inlent and outlet of rad.
No safetyvalve that I could see.
Can't give you the in and out temps just now, as the tiler and decorater have asked for the fire not to be lit until they are finished. Probably the weekend.
Will let you now the outcome after the weekend.
Cheers.
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