boiler query

Joined
7 Nov 2010
Messages
95
Reaction score
5
Location
London
Country
United Kingdom
I have an old single pipe system and recently had a new vaillant combi fitted.

I am now in the process of changing the rads myself and was wondering if i could if i turn the heating off at the wall mounted wireless remote can i keep the boiler on for hot water to the sinks etc whilst their is no water in the radiators.

The system has frost protection as the boiler is in a out house but would assume its not really cold enough in London now for it to kick in.
 
Sponsored Links
Joined
15 Dec 2007
Messages
8,011
Reaction score
2,112
Location
Bristol
Country
United Kingdom
If you are changing the rads, you will be draining down the system. The boiler won't work, as it will detect low system pressure.

If the work will take some time, you could bridge the ch flow and return pipes near the boiler, to give you a small loop, then pressurise this.

If you can, scrap the one pipe system as well, and put in a 2 pipe layout.
 
Joined
7 Nov 2010
Messages
95
Reaction score
5
Location
London
Country
United Kingdom
Thanks for the quick reply.

Can you explain why , as its good to know the reasons if only just to increase my my knowledge.
 
Sponsored Links
Joined
7 Nov 2010
Messages
95
Reaction score
5
Location
London
Country
United Kingdom
Thank you

It wont take long as im only doing 6 down stairs at present so will refill the system tomorrow. The others will be done when i start decorating the other rooms.

Just didnt want to get up with no hot tap water.
 
Joined
15 Dec 2007
Messages
8,011
Reaction score
2,112
Location
Bristol
Country
United Kingdom
Be aware that if you are adding TRVs to the new rads, one pipe systems don't always work well with them.

You can get special one pipe TRVs, but they aren't cheap.
 
Joined
7 Nov 2010
Messages
95
Reaction score
5
Location
London
Country
United Kingdom
If you can, scrap the one pipe system as well, and put in a 2 pipe layout.

Will be.

Im looking to see if i can do it a section at a time. If i cant it will have to wait till summer or spring as it will take to long to repipe the whole system and the wife will not go without hot water or heating for long .
Be aware that if you are adding TRVs to the new rads, one pipe systems don't always work well with them.

Attaching them to the rads but gonna use the alternative head until i can switch fully over to 2 pipes.

I take it that is ok ?
 
Joined
21 Feb 2011
Messages
31
Reaction score
1
Location
Hampshire
Country
United Kingdom
vaillants can be run on just hot water. isolate at flow and return valves and keep pressure in the boiler when draining heating cuircuits
 
Joined
15 Dec 2007
Messages
8,011
Reaction score
2,112
Location
Bristol
Country
United Kingdom
Attaching them to the rads but gonna use the alternative head

Not sure what you mean by alternative head? The apertures in ordinary TRVs are too small for one pipe. You may find that they take a long time to heat up the rads. Bigger rads will be quite cool.

If it was me, I would leave fitting the TRVs until you start swapping to 2 pipe.
 
Joined
7 Nov 2010
Messages
95
Reaction score
5
Location
London
Country
United Kingdom
Attaching them to the rads but gonna use the alternative head

Not sure what you mean by alternative head? The apertures in ordinary TRVs are too small for one pipe. You may find that they take a long time to heat up the rads. Bigger rads will be quite cool.

If it was me, I would leave fitting the TRVs until you start swapping to 2 pipe.
In the box there is another cap , that screws on in place of the control head and if screwed on all the way it acts on the plunger cutting off the flow to allow radiator removal. .

If it is fitted instead of control head but no tightened i asume flow will be retained. ?
 
Joined
15 Dec 2007
Messages
8,011
Reaction score
2,112
Location
Bristol
Country
United Kingdom
The problem with ordinary TRVs and one pipe systems is nothing to do with the head. Its the narrowness of the aperture inside the actual metal valve bit that disrupts the thermo-syphon effect that one pipe rads rely on.

You can turn the head up as high as you like, you can't enlarge the narrow passage.

See how much broader the body is on a one pipe TRV.

http://www.radiators4you.com/acatalog/Danfoss_RA-G_Valve_Bodies_For_1_Pipe_Systems.html

You may find that your new rads and standard TRVs are a tad disappointing. What valves are on the old rads at present?
 
Joined
7 Nov 2010
Messages
95
Reaction score
5
Location
London
Country
United Kingdom
The problem with ordinary TRVs and one pipe systems is nothing to do with the head. Its the narrowness of the aperture inside the actual metal valve bit that disrupts the thermo-syphon effect that one pipe rads rely on.

You can turn the head up as high as you like, you can't enlarge the narrow passage.

See how much broader the body is on a one pipe TRV.

http://www.radiators4you.com/acatalog/Danfoss_RA-G_Valve_Bodies_For_1_Pipe_Systems.html

You may find that your new rads and standard TRVs are a tad disappointing. What valves are on the old rads at present?
Thank you .
Looks like its back down the shop tomorrow
 
Joined
7 Nov 2010
Messages
95
Reaction score
5
Location
London
Country
United Kingdom
So now i am confused .


Two small radiators in one room are fed directly from one to the other ,the sign of a one pipe system ,correct ?

Just lifted the floor boards in hall and that one has a 15mm feed coming in from a 22 mm pipe but then comes out of the radiator and into another 22 mm pipe running along side the other. .

Could the system be mixed between the 2.

No rads in the house feel cold and it previously had a tank in the loft
 
Joined
10 May 2006
Messages
11,968
Reaction score
1,580
Location
Merseyside
Country
United Kingdom
It's a normal two pipe system, but someone has just fed the two small rads in series off the flow and return.
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Top