Strange one regarding heating, rads hot without a pump!

Redisle

Bit of backround:

We have a 2 coil copper tank, one coil connected to oil heating, the other connected to a back boiler in the fireplace. This fire is lit most nights and heats the rads and the tank.

A few months ago we converted our attic and added heating upstairs. The water resevoir tank for the heating system was moved up to the crawl space above our new conversion and a plumber installed a number of new radiators upstairs. The house was plumped first day with an option to add upstairs heating so there were 4 pipes already in place but not connected to anything (2 for back boiler, 2 for central heating). So the upstairs radiators were connected to these pipes (He only seems to have used one of the pipes for the back boiler side of it and has a pressure release valve on the other but both pipes for the central heating are used)

He told us first day that our boiler wouldn't be enough to heat all the rads in the house together so we turn a few off downstairs when we are using the ones upstairs. When he first installed the system we ran a few tests. We turned off all the rads downstairs and switched on the central heating. Of the 4 rad's upstairs only 2 heated correctly. When using the back boiler and associated pump they would heat up slightly but nowhere near the ones downstairs.

Anyway we made a strange discovery tonight. Basically we had the central heating on for a while and the fire lighting and the water in the cylinder was near boiling, the heating was then switched off but the back boiler pump was not switched on. We were upstairs and noticed that all the rad's were really hot.. they had never been this hot before when using the back boiler pump or central heating and this was with no pumps switched on.
At this point all the radiators downstairs were cold and the ones upstairs were very hot.
We then switched on the pump for the back boiler and the rads downstairs heated up but the ones upstairs cooled down to tepid.

Basically Im guessing this is the result of convection currents driving hot water from somewhere and pumping it around the rads upstairs...or it's water returning to it's own level.. not sure really,dosen't really make much sense to me.. is it possible it was plumbed in wrong? What we really want is to have all the (switched on) rads to be hot at the same time from the back boiler and the heating.. not just upstairs or just downstairs..

Does anyone know how to solve this one?

Thanks

Redisle

Can anyone make sense of this?

As another test today we did not use the heating at all and just lit the fire. The rads upstairs heated again with no pump in use and all the downstairs ones remained cold..

Any ideas how to fix it so all the rads can be hot?

JamesM

Seeing that none of the plumbers have commented on this, I'll say that it is almost impossible to tell exactly what is happening without seeing the layout.
It would seem that the pump is working against the natural gravity flow of the hot water from the back boiler.
I don't think that the radiator system upstairs would usually be divided into 2 parts, ("there were 4 pipes already in place but not connected to anything (2 for back boiler, 2 for central heating))".
As I said, I believe that people have not answered, because they would need to see the system.
Jim.

Redisle

Ok fair enough, thanks for the reply. I think you may be right that it's unusual for it to be divided, when the plumber was installing the heating upstairs he first used just 2 pipes and the rads were then only heating from one source, Then he connected one of the other 2 pipes and put a pressure release valve on the 4th, I think he may have been chancing his arm with this.. Il throw up a few pics here to see if it helps any bit but if not I guess Il have to get that plumber back to try and sort it out.

311

Redisle this is normally the type of stuff I work with all the time (out sick at the mo) ,but it's still very hard to make out whats going on.
When radiators are piped wrong ,it usually results in the problems your having.

In your first photograph ,the return pipe is going down into the floor. Is there any pipes to the right (around back boiler) that are going upstairs ?

Redisle

No there is no pipes going from around the back boiler upstairs, just the two that also connect to the coil in the tank..

The only pipes going to the attic regarding heating are the ones I showed you above and the supply lines for the water tank.