Any heating engineers about?

[Vagrant No2]

A quick question regarding gas fired open vent central heating.We have 22mm feed and return running through upstairs and down stairs in the house . When the 22 mm pipes get to the lounge they then T off through the understairs cupboard in 15 mm pipes and then through the wall into the dining room across the under the floor to the rad on the wall then through to the office . Prob is these rads never seem to get hot and the rooms always seem cold . System has been flushed and rads temp is even across the rads . If I was to replace the 15mm sctions of pipe with 22mm pipe until I reach these 2 rads would this improve their heat output ?

[darkdezigns]

have u tried bleeding the air out of rads?

[mick p]

Possibly,Try altering the speed of the pump, either to no.1 or no.3

[grabeck]

you could try cranking down the return valve a little on the rads nearest the boiler or upstairs(the hottest ones) to send more hot water to cooler ones.

[Tiger]

Changing it too 22mm would definately help but you should try balancing the system first as this will not cost anything. Just an hour messing about with the rad valves.

Pm me if would like me to explain

[Tiger]

you could try cranking down the return valve a little on the rads nearest the boiler or upstairs(the hottest ones) to send more hot water to cooler ones.

basically What he said

[mckirdy-services]

A quick question regarding gas fired open vent central heating.We have 22mm feed and return running through upstairs and down stairs in the house . When the 22 mm pipes get to the lounge they then T off through the understairs cupboard in 15 mm pipes and then through the wall into the dining room across the under the floor to the rad on the wall then through to the office . Prob is these rads never seem to get hot and the rooms always seem cold . System has been flushed and rads temp is even across the rads . If I was to replace the 15mm sctions of pipe with 22mm pipe until I reach these 2 rads would this improve their heat output ?

Whats the BTU requirement for the rooms? I cant think off hand what the load is for 15mm pipe( basically the maximum amount of BTU / watts (whichever you prefer) that can be pumped through the pipe at the system operating temp) Check and calculate this before replacing all the 15mm pipe as you might only need to upgrade a few meters. You might find that is just needs balancing properly, have you got TRV's fitted? Also are the radiators sized correctly? Has it been (Properly power-flushed and each section checked with a TDS meter?).
You can get a rough guide to the BTU requirement on here
http://www.radcalcs.com/
(it does tend to air on the side of caution by about 10%+ as you cannot enter the specific U values for the building fabric.


There is a little information on my company's website http://www.mckirdyservices.co.uk go to the power flushing page.

Most likely system not correctly balanced and undersized pipework to rads.

On the other rads close the lock shield valves and see if the radiator gets up to temperature and the room. If so then you should be able to balance the system depending on if you have trv's fitted?

pm me if you want further info, I'm not too coherent at moment as have a headache and about to go to sleep.

[Tiger]

Whats the BTU requirement for the rooms? I cant think off hand what the load is for 15mm pipe( basically the maximum amount of BTU / watts (whichever you prefer) that can be pumped through the pipe at the system operating temp) Check and calculate this before replacing all the 15mm pipe as you might only need to upgrade a few meters. You might find that is just needs balancing properly, have you got TRV's fitted? Also are the radiators sized correctly? Has it been (Properly power-flushed and each section checked with a TDS meter?).
You can get a rough guide to the BTU requirement on here
http://www.radcalcs.com/
(it does tend to air on the side of caution by about 10%+ as you cannot enter the specific U values for the building fabric.


There is a little information on my company's website http://www.mckirdyservices.co.uk go to the power flushing page.

system has been flushed and even temp accross rads

Is this a blatent add for your services

Most likely system not correctly balanced and undersized pipework to rads.

On the other rads close the lock shield valves and see if the radiator gets up to temperature and the room. If so then you should be able to balance the system depending on if you have trv's fitted?

pm me if you want further info, I'm not too coherent at moment as have a headache and about to go to sleep.

All thats lovely in an ideal world and assuming the system was designed properly in the first place.

Are you tryin to con fuse the man, Laymen's standard size house 75% 22mm pipe On main runs tailing of 25% 15mm to rads

[Koi]

All thats lovely in an ideal world and assuming the system was designed properly in the first place.

Are you tryin to con fuse the man, Laymen's standard size house 75% 22mm pipe On main runs tailing of 25% 15mm to rads

Agreed, as already said sounds more like the system needs balancing due to incorrect pipe work or the pump is to big and pumping to fast therfore water taking least resistance round 22mm pipe.

As a test rick close off other rads, this will force water round those not getting hot, once hot just crack open the other rads enough so the hot water flows through them.

[hilly64]

As a rule of thumb on domestic 15mm will carry upto about 4kW and 22mm upto about 8kW ish but then that depends on lengths of run, bends, fittings etc. If you post the rad sizes inc single/double panel and whether they have fins attached and to which sides I can give you approx outputs.

In theory you can put bigger and bigger pumps on and increase this capacity proportionately however the limiting factor is that you don't want water velocity in the pipes going much above 2m/s as they then get noisey.

Sounds very much like balancing and that the run you are talking about is maybe the furthest from the boiler and with the most resistance due to pipework size and fittings making it the index run.

Just check for blockages by closing all rad valves and opening the troubled rads fully ie both the wheel head (TRV if fitted) and lockshield. Run the boiler up with pump on max speed and ensure rads get hot. Also make sure there is no air in the system and that there is no high points on the pipework where air can collect and not vent out through rads etc. Also check pumps is working.

If rads get hot then move on to balancing.
As previously stated start by setting pump to speed 3. Open all the wheel head valves or thermostatic radiator valves if fitted. On the opposite side of the rad is the lockshield valve(usually need to remove top to adjust).

Close all lockshield valves then starting at the rads nearest the boiler crack open the valve maybe just half a turn. Then move to the next rad and add a further half turn continue working away from he boiler rad by rad. You may find that the troublesome rads need to be wide open and that others will be somewhere in between. Its simply a case of running around checking whilst the heating is on. If you have closed the valve too much this will show its self as a cooler radiator at the middle of the bottom.

Once balanced reduce pump speed whilst still maintaining performance.

Hope this helps

[Vagrant No2]

OK , the rads do get hot in both rooms and I am sure it may just be the locksheilds need setting up . No power flush done , but used some really good stuff I know works quite well (but obviously not as good as power flush) and it shifted loads off black muck out .
I always got confused which locksheilds needed to be open most , nearest or furthest from boiler , you have now confirmed this for me.
I need to drain and refill system again this weekend to fully flush out the cleaning stuff and then refill and add the treatment stuff.
So when done I will try and adjust locksheilds. Failing that I may just change the pipe work for 22mm for piece of mind .
And , yes I got TRV fitted to all rads except bathroom as I changed for a towel rad and kitchen which has a designer vertical panel rad.

[Tiger]

everything you have said all sounds good, if you are getting even temps accross rads then you shouldn't need power flush but if you feel like playing i can drop my kamco power flush of with jotto one weekend if you like

[Vagrant No2]

everything you have said all sounds good, if you are getting even temps accross rads then you shouldn't need power flush but if you feel like playing i can drop my kamco power flush of with jotto one weekend if you like

Cheers for the offer , depending on how it all goes I may take you up on the offer before end of this year.
You are always welcome to visit here when up Gedney as only 12 miles from Jon

[hilly64]

I doubt you need to powerflush or change the pipework. If its only feeding a couple of rads, they are not huge and the run is not massive it shoud be ok.

If any rads are suspect give them a run through with hose outside and provided there isn't a mass of crud you should be ok.

Then try balancing as described and adding some inhibitor wouldn't be a bad idea.

[mckirdy-services]

HI, I'm feeling better now i have had a few hours sleep,

Just read through the last replies pretty much everything has been covered. However have you checked what temp the radiators are getting to? Compare the what the boiler is putting out on the flow if there is no more than a 10* drop then it might just be that the radiators are undersized.