Adding radiator to flow and return of oil boiler

[thewickedpickett]

I have recently had my old non condensing oil boiler in external garage changed to a gas combi elsewhere in house.

I have been left with these pipes which are dead legs and I assume are the flow and return the old oil boiler used. I want to add a radiator to help add some heat to the garage. Can I simply add a radiator using hep20 pipe with TRV and lock shield etc? Do I need to drain the system? Any other pit falls?

 

[cross thread]

I would check with your installer if they are a flow and return, if they are you could add a radiator.

 

[thewickedpickett]

Thanks. I think they are. There was some talk of the installer putting a radiator in but it never materialised.

 

[Hugh Jaleak]

If you're sure they are Flow and Return, then adding a Rad shouldn't be too much of an issue. Unsure why though they've fitted a drain off to one and not the other.

 

[thewickedpickett]

Is there a way to tell which is flow and which is return? I had assumed the drain off one would be flow?

 

[Harry Bloomfield]

Is there a way to tell which is flow and which is return? I had assumed the drain off one would be flow?

Only by either connecting a radiator, and see which pipes become warm first, or trace them back to a point where one of the two becomes warm, when the heating is first turned on from cold.

 

[Exedon]

If all your doing is fitting a rad which is flow/return is immaterial as long as you use a bi directional trv.

 

[thewickedpickett]

I have a few radiators that the installer fitted the TRV on the flow and the only issue I’ve had is I find them harder to balance but that may just be me.

 

[Madrab]

Is it a combi or a heat only/system boiler with a cylinder?

If the latter then need to watch where that return sits on the system as it could end up with reverse circulation, if it's after the cylinder return. (see the 3 tee rule)

 

[thewickedpickett]

It’s a combi so hopefully no major issues. I can’t find out if I need to drain the system? As those pipes are dead legs I don’t think they have water in them so presumably wouldn’t need to drain?

 

[Madrab]

OK, as a combi then no real concern there, still need to see where in the system it connects though. Why heat a garage though, unless it's to be sealed/insulated etc as a room otherwise it would be an awful waste of energy IMO.

I can’t find out if I need to drain the system

If they are still connected to the system then yes you will need to drain down.

A dead leg doesn't mean the pipe is empty, it just means that the water in it doesn't move/flow.

 

[Hugh Jaleak]

I have a few radiators that the installer fitted the TRV on the flow and the only issue I’ve had is I find them harder to balance but that may just be me.

If they're not Bi Directional, and fitted on the return, then the flow will be trying to force the Valve shut all the time. Came across a WB Combi in a Rental Property, with some TRV's the wrong way round, even the Neighbour phoned the Landlord to complain about the noise, after he told the Tenant it was nothing to worry about!

 

[thewickedpickett]

OK, as a combi then no real concern there, still need to see where in the system it connects though. Why heat a garage though, unless it's to be sealed/insulated etc as a room otherwise it would be an awful waste of energy IMO.

If they are still connected to the system then yes you will need to drain down.

A dead leg doesn't mean the pipe is empty, it just means that the water in it doesn't move/flow.

I have thought about this a lot but it’s really just to take the chill out for my small gym out there. Alternative is an electric heater of some description but I figured electric costs more than gas and I’ll have the gas heating blasting anyway when it’s cold? Also have the issue of turning electric heaters on and off prior to going out to the gym etc.

I do plan to add some sort of insulation boards to the roof at some stage but it may not add a lot of heat retention.

The flow and return are far away from the gas combi if that helps. Combi in loft and flow and return in external garage. One thing I’ve noticed is air comes out of the drain valve on one of the pipes. I assume after some time water will come out.