radiators working intermittently

[ollieslad]

Hi Folks. New member so would really appreciate any advice.
Im quite handy with a lot of aspects of plumbing and as such decided to replace some radiators.
I had to do this over a period of time as didnt have the funds to buy all rads at once. The old rads were only singles so decided to upgrade them all to doubles as i thought its best to have a rad that can easily cope with the size of room that you can turn down rather have one that just about copes.
Ive done these over a period of about eighteen months but have noticed that the downstairs seem to work when they want. the hall one seems to work for a bit then seems to drop right off where as the large one in the living room just seems to kick out the maximum at all times no matter what.
I thought there may be air in the system and have tried bleeding but when i open the bleed screws water is there straight away on all of them. Then i had a thought that the trv on the living room my not be bi directional. Checked this and sure enough even though it is a new trv the side with the thermostat heats up first but has a down arrow on the body so is on the wrong side.
Could this be the problem for the intermittent rads and full heat out of the living room one.
I can change to a bi directional no problem but just wondered if this would be correct.
Apologies for the long first post and if its not technical as i say im just a diyer lol.
Many thanks

 

[SimonG]

Have you balanced them?

Welcome along 🙂

 

[shyguy2005]

What brand is the TRV currently on? Are you sure there isn't 2 arrows on them? Also as SimonG says have you balanced the rads?

Welcome to the forum. :welcome:

 

[ollieslad]

hi simon
Many thanks for getting back to me.
Im not too sure how to balance them. Im ok fitting rads and taps etc and draining down and bleeding the system but this is new to me lol.
I have read about balancing the system is this about shutting them down?

 

[Dotty]

Read this.

http://www.ukplumbersforums.co.uk/central-heating-forum/87115-croppies-balancing-thread.html

 

[ollieslad]

Hi shyguy. Thanks for the welcome.
the trv is a lifestyle one. think i got it from screwfix. ive just peeled back a bit of the ptfe tape and there is indeed two arrows so it is bi directional so that put and end to my epiphony lol.
its really weird as when the system is drained down the rads upstairs take ages to get going and ive had had to close the downstairs ones to get them going. i think part of the problem maybe that they are on microbore pipe.

 

[Rickster123]

You've doubled the size of all radiators on microbore pipework? How many have you changed and what sort of sizes?

 

[Dogby]

Being micro ore ther is probably still air in the system, shut all down and work through 1 by 1 to help push the air through, then as above balance the system , failing that convert it to a sealed system

 

[ollieslad]

many thanks croppie.
ill have a go at this. ill have to be like lightening to get round them all lol

 

[ollieslad]

many thanks croppie.
ill have a go at this. ill have to be like lightening to get round them all lol

 

[Rickster123]

convert it to a sealed system

On a microbore system? I wouldn't personally.

 

[ollieslad]

they are all similar sizes just doubles upstairs. the ones downstairs are on 15mm pipe apart from the one in the living room which gets hotter than versuvius lol thats on microbore as well.

 

[shyguy2005]

What boiler do you have ? And what size? I.e. 15kw etc? Have you swapped the rads upstairs from singles straight to doubles but kept them the same length?

 

[joni os]

The fact you have one rad extra hot demonstrates you have capacity in system. There is a possibility that the theoretical output of the rads exceeds the capacity of pipes to supply, but ignore theory and just follow Croppie's post, but with greater difference in temp between flow and return at rad. if 12 C cannot be achieved. The advantage of your oversize rads is boiler stays in condensing mode longer.

 

[JCplumb]

ive just peeled back a bit of the ptfe tape and there is indeed two arrows so it is bi directional so that put and end to my epiphony lol.

Where was/is the PTFE if it was obscuring the arrow embossed on the valve body? It's only needed to seal the rad tails, and with new valves/olives you shouldn't need any anywhere else.
If you've got it wrapped round the outside of the valve body, where else do you have it? Possibly on the stem of the tail that goes into the valve and thus obstructing the flow of water?
It does sound like a balancing issue, but make sure the basics are right first or you may never get it sorted.

 

[ollieslad]

hi shy guy
all the upstairs ones were straight swaps same size just to doubles. The one in the living room was swapped for a slightly smaller one but a double, just altered the pipework slightly and the one in the hall was just changed to a new double. Im not sure of the size of boiler but i do know that it is a vaillant turbomax plus 824e if that makes sense.
many thanks

 

[shyguy2005]

hi shy guy
all the upstairs ones were straight swaps same size just to doubles. The one in the living room was swapped for a slightly smaller one but a double, just altered the pipework slightly and the one in the hall was just changed to a new double. Im not sure of the size of boiler but i do know that it is a vaillant turbomax plus 824e if that makes sense.
many thanks

Right ok, so have you tried balancing the rads yet?

 

[ollieslad]

thanks jc
I know its not blocking the flow of water. whenever i have put new valves on i always make sure it starts flush with thread but take it right back. if anything i always use too much lol

 

[ollieslad]

Havent had a chance yet with work but ill try and have a go over the weekend. i have closed the return valve so its almost shut and see how that goes.