by chris_on_tour2002 »
Tue Dec 02, 2008 12:57 am
leaving aside the ethical argument for a moment (before a hairy lentil eater in sunday market knitwear picks me up on it :D) - if we all balanced our heating systems for optimum performance then perhaps the glaciers wouldn't be retreating at the rate that they currently are, but let's keep it technical for the purposes of this discussion.
adamsheating - if you always balance your new installs when TRVs are used then good for you! cannot be faulted and you are surely in the minority.
with permission i would like to retract my use of the word "should" from my post. though in my defence there are TRVs available now that categorically state that the lockshield valves remain fully open (i admit that i was not assuming that these were the type fitted in this case). i found this extract from GN3 which the administrator will hopefully permit as it's only a tiny extract from the overall article:
"One of the main causes of poor TRV control is the UK use of a minimum pipe size of 15mm/½". In general, UK ½" TRVs passing approximately 3600W when fully open (at system start up) in a 11°C delta T situation with a typical pressure differential of 10kPa. Since the average radiator size is 1200W, there are some 2400W to be taken out. This “Overflow” should, in theory be regulated out by means of the radiator lockshield valve, but this is almost never done.
The selecting of TRV bodies having variable Kv values is the ideal solution. This easy to regulate method of optimising the individual radiator flow requirement gives the site engineer the opportunity to preset each valve relative to a heat output from the radiator schedule. The lockshield valve remains fully open."
additionally there is a recommendation to fit DPCVs to all systems fitted with TRVs to prolong the life of valves and other system components.
the purpose of the reply was to try to put midknight's mind at ease a little (though this thread may have had the opposite effect by now!) and frankly HTG had already covered it quite nicely in his reply: "Quite common with new installations, he's probably just an installer - wants to be in and out. If all the radiators get hot, and the rooms heat up - then the system works. But to get the best from the system you want about 12 degree temperature difference between the flow and return to each rad..."
in hindsight i should have left well alone!
to answer midnknight's final question, no it is not best practice to leave the lockshields fully open though it is, rightly or wrongly, common practice.
balancing your system will offer improved longevity, efficiency and running costs - though by how much is impossible to say. you'd also be helping the good people of norfolk to get a decent night's sleep in, happy in the knowledge that you have kept the north sea from lapping over the front doorstep for another night. and on that thought, i'm off to buy a fleet of TVRs :D
