So you just bought or moved into the house, switched on the heating, and only some radiators are completely hot, while others are lukewarm with coldspots in the middle, and the gas/oil bill was massive while most rooms are struggling to reach even 18C and pose a heath risk? The previous owners/tennants told you that this house will need a new CH system and been quoted 5K+ GBP for the Job?-> First try flushing EVERYTHING thorogly using the following protocol:
(Start NO later than Friday evening, if planning to do it on the weekend). Also don't do it if there is -10 - -20 degrees forecast for the weekend :yes:
1. Remove the sludge from the overhead tank (on the open system).
Get yourself a strong mate, and:
2. Close both rad feed taps, and Take off EACH Radiator, and do the following with it:
7. Hang/connect all the rads back.
11. If all is OK on the next day - doze the system to the gills with the favorite inhibitor, and put a few pairs of the neodymium magnets (from eBay (N40+, 6mmX10mmX30mm)) on the boiler's return pipe (copper/plastic), so they attract and love each other across the pipe. The magnetic field direction angle should wary by 90-180 degrees between the pairs. Also do the same with the cold water feed (unless you already have a good mangetiser on it).
PS: While it is quite labor intensive, you and your's mate are not very likely earn yourself 500 GBP net over the weekend with average UK wage. Also it would save you the trip to the gym. And you are quite likely to forget about your's radiators for the next 5-30 years...
MOD's footnote.
As with all DIY there is a huge element of risk involved. While we cannot stop you attempting this procedure you should be fully aware that you could be making a bad situation far worse. You could also be running the very real risk of dripping black radiator water round the house. Then not only will you not get fed but you'll find your bags packed and by the front door.
Powerflushing may look easy but there are far more things to go wrong than right.
As always the UKPF stance is get a professional in.
(Start NO later than Friday evening, if planning to do it on the weekend). Also don't do it if there is -10 - -20 degrees forecast for the weekend :yes:
1. Remove the sludge from the overhead tank (on the open system).
Get yourself a strong mate, and:
2. Close both rad feed taps, and Take off EACH Radiator, and do the following with it:
a. Take the rad outside. Put it on the boards or grass.
b. connect it to the source with GOOD FLOW RATE (like 3/4 - 1 inch garden hose or 1-4KW (3phase motor if available :yes🙂 6bar+ pump linked to a but/pool/clean pond (without fish/life)/well).
c. turn the rad upside down, fill it with water, wait untill the water runs clear, than invert it and wait for the clear, than again invert and bang on it with the rubber mallet through the wooden board (to protect the paint) or use SDS MAX mallet attachment :yes:, untill the water is clear.
d. turn it in the normal and bang it again untll clear.
e. Stop water, drain it (so there is air inside), and connect it again in the NORMAL posiotion so it is full of air, turn the water on a full blast, so it has to flow through the bottom bit. Bang-Bang until clear.
f. Go to c-e (repeat 2-3 times if needed, can also change the flow direction to the oposite). Agitating the half-full rad also may help.
g. If wanted wash the exterior finish with pressure washer or hose. Don't forget to wash out the dust from the inside of it too.
h. Clean that bleed valve, if needed...
3. For each radiator pipe connection do the following:b. connect it to the source with GOOD FLOW RATE (like 3/4 - 1 inch garden hose or 1-4KW (3phase motor if available :yes🙂 6bar+ pump linked to a but/pool/clean pond (without fish/life)/well).
c. turn the rad upside down, fill it with water, wait untill the water runs clear, than invert it and wait for the clear, than again invert and bang on it with the rubber mallet through the wooden board (to protect the paint) or use SDS MAX mallet attachment :yes:, untill the water is clear.
d. turn it in the normal and bang it again untll clear.
e. Stop water, drain it (so there is air inside), and connect it again in the NORMAL posiotion so it is full of air, turn the water on a full blast, so it has to flow through the bottom bit. Bang-Bang until clear.
f. Go to c-e (repeat 2-3 times if needed, can also change the flow direction to the oposite). Agitating the half-full rad also may help.
g. If wanted wash the exterior finish with pressure washer or hose. Don't forget to wash out the dust from the inside of it too.
h. Clean that bleed valve, if needed...
a. Attach an adapter with a bit of hose and open the tap fully into a 20L bucket, until water runs clear. You can also use 6 pints+ organic milk bottle(s) if you don't have a hose with the adapter.
b. Open the top up valve fully for the closed system.
c. Open the tap fully untill water runs clear or the container is full.
d. Repeat c unill clear, can also bang on the pipe gently.
e. If there is no flow - try going into the fully open valve with steel wire or rope (or tiniest drain cleaner 🙂. Remove the valve to gain better access to the pipe.
Hold the hose/thumb/cloth/bucket ready if the fountain of happy black flow emerges suddenly :yes: If not - try rigging up the pressure washer... (but open the neighboring radiator flow or return, so your's system doesn't go bust).
4. If you have underfloor heating and it had sludged up - connect one end to the 2.b (hose), and the another end into the drain or garden.b. Open the top up valve fully for the closed system.
c. Open the tap fully untill water runs clear or the container is full.
d. Repeat c unill clear, can also bang on the pipe gently.
e. If there is no flow - try going into the fully open valve with steel wire or rope (or tiniest drain cleaner 🙂. Remove the valve to gain better access to the pipe.
Hold the hose/thumb/cloth/bucket ready if the fountain of happy black flow emerges suddenly :yes: If not - try rigging up the pressure washer... (but open the neighboring radiator flow or return, so your's system doesn't go bust).
b. Flow until clear.
c. Try again in the opposite direction.
5. Do the upgrades (optional): Now is the time to install those missing thermostatic valves (except room(s) with the thermostat) or fix up/replace leaking rad taps.c. Try again in the opposite direction.
If there is a tiny rad against the internal wall, 60 cm above the floor on the ground floor lounge with the French door, and someone had his feet frostbitten in the winter there, than up-size it to 2KW per 10M^2 and move it to under the window, no higher than 15cm from the floor.
Also if someone before had put 35KW boiler on a 10m run of 15 mm pipe, now is the time to replace it with 28 or 22 mm one.
Remember the BIGGER the rads, the MORE efficient the condensing boiler is (so the lower your's heating buill at the same room temp (up to 15% down). The house should reach 20degrees, with the boiler's flow at 40degrees, when there is 0 outside. So do upgrade those tiny ones in the corner rooms...
6. Check/flush HW cylinder and it's coil (if you have one). Also the boiler if it is coal/oil/wood or (your's mate is Gas Safe Reg). Brush/hoover/Pressure washer can be helpful there too, after all electrical components are isolated and separated. Soot/dust/dirt is a good heat insulator...Also if someone before had put 35KW boiler on a 10m run of 15 mm pipe, now is the time to replace it with 28 or 22 mm one.
Remember the BIGGER the rads, the MORE efficient the condensing boiler is (so the lower your's heating buill at the same room temp (up to 15% down). The house should reach 20degrees, with the boiler's flow at 40degrees, when there is 0 outside. So do upgrade those tiny ones in the corner rooms...
7. Hang/connect all the rads back.
a. Clean EVERY connector surface with the wire dish sponge. Do it in the concentric motion (not radial!).
b. Use Fernox LSX or similar on EVERY threaded/compression joint (and forget about the leaks...).
c. Connect the rads.
8. If there are some soldering jobs to be done, than drain the system and do it.b. Use Fernox LSX or similar on EVERY threaded/compression joint (and forget about the leaks...).
c. Connect the rads.
Also check the pressure in the expansion tank/weasel (if on sealed system). Use a bike/car pump to top it up to the 0.8 - 1.3 bars.
9. After opening of all rard taps, fill the system.
a. Afer all air removed/bleed and pressure topped up,
b. Run the boiler on the max temp for 1-3 hours, and check for any leaks.
c. Once it is cooled, now is the time to ballance it - leave all downastairs valves open, and close upstairs ones, then open by 1-3 turns each. The smaller rad, and the closer it is to the boiler, the less it should be open. Towel rail may need 1/5 -1/2 turns only.
d. Switch the system on medium setting (40 - 50 degrees). As it is warming note, which rads warm up first, those may need to be closed a bit more.
e. You aim for 10-20 degrees differential between the radiator's flow/return. Finetune based on the ammount of the heat required for each room.
f. Detect and close down the ones which have almost even temperature on the flow/return - those are bypassing the heat flow - so close them more.
10. Hope now you are warm and it is still Sunday evening. Ask your's missus to cook you a dinner (or breakfast if it's already Monday morning).b. Run the boiler on the max temp for 1-3 hours, and check for any leaks.
c. Once it is cooled, now is the time to ballance it - leave all downastairs valves open, and close upstairs ones, then open by 1-3 turns each. The smaller rad, and the closer it is to the boiler, the less it should be open. Towel rail may need 1/5 -1/2 turns only.
d. Switch the system on medium setting (40 - 50 degrees). As it is warming note, which rads warm up first, those may need to be closed a bit more.
e. You aim for 10-20 degrees differential between the radiator's flow/return. Finetune based on the ammount of the heat required for each room.
f. Detect and close down the ones which have almost even temperature on the flow/return - those are bypassing the heat flow - so close them more.
11. If all is OK on the next day - doze the system to the gills with the favorite inhibitor, and put a few pairs of the neodymium magnets (from eBay (N40+, 6mmX10mmX30mm)) on the boiler's return pipe (copper/plastic), so they attract and love each other across the pipe. The magnetic field direction angle should wary by 90-180 degrees between the pairs. Also do the same with the cold water feed (unless you already have a good mangetiser on it).
PS: While it is quite labor intensive, you and your's mate are not very likely earn yourself 500 GBP net over the weekend with average UK wage. Also it would save you the trip to the gym. And you are quite likely to forget about your's radiators for the next 5-30 years...
MOD's footnote.
As with all DIY there is a huge element of risk involved. While we cannot stop you attempting this procedure you should be fully aware that you could be making a bad situation far worse. You could also be running the very real risk of dripping black radiator water round the house. Then not only will you not get fed but you'll find your bags packed and by the front door.
Powerflushing may look easy but there are far more things to go wrong than right.
As always the UKPF stance is get a professional in.
Last edited by a moderator:
