All 2 entries tagged Diy

Drain central heating system

Writing about web page http://www.letsfixit.co.uk/html/central_heating.html

Today I drained the centre heating. Steps as follows:

• Turn the centre heating off.
• Open the outside valve for 5 minutes.
• Open the vent (bleeding point) on ALL radiators. Might need to open the thermostat as well
• Pour inhibitor in one of radiator
• Turn off the outside valve. and turn off some vents
• Turn the two inlet valve under boiler and pressure bar is above 1.0
• Check whether water from vents then close it
• bleeds vadiators
• run for a while

A good article copied from somewhere

• BALANCING, and LOCKSHIELD VALVES (LSV’s): Most standard radiators will have one valve each side (see pictures HERE). One is the “normal” one for turning individual radiators on and off, and the other one (the LSV) is either used for balancing the flow to get even temperatures between rooms, or for isolating a radiator for removal (decorating etc), when both valves are off. If you have to do this, ensure that you remember how many turns the LSV was from the closed position, so that you can put it back to its previously balanced state.
  Usually the FIRST radiator in any zone/loop has the most flow rate, and the last one the least, unless well balanced. Always BALANCE the flows with any TRV heads fully open, or the adjusting head unclipped from the valve. Try to aim for about 10 to 12 degrees C (17 – 20 F) difference between the incoming and outgoing water pipe.
  A thermocouple meter is “OK” for this (L55AN from MAPLIN), but Maplin also sell an IR (Infra Red) meter (Number N20BB), for about £30, that is quicker to sense, and does not require close full contact with the pipe. ETI LImited also sell a very good IR Thermometer (the TN2), for about £39 with delivery and VAT. There is also a TN1, at about £23. Both appear to be available at this site link: http://www.fluesystems.com/thermometer/ There are alternative ones mentioned on the following site too from about £27: http://www.thermometersdirect.co.uk/acatalog/Thermometers_Direct__In frared_thermometers_6.html

• If you drain and remove a radiator, and your system is a mains pressurised combi boiler, then after refitting and bleedind the radiator, you will find that the pressure will have dropped. Repressurise using the COMBI FILLING LOOP (near the boiler or pump), and open the 2 control valves until the pressure is between 1.2 and 1.5 BAR (or whatever is reommended in you manual). Close off the 2 valves, and check that the boiler fires up. Some boilers will not fire up if the pressure is too low.

• If yours tends to “kettle” even on the lower settings, this may indicate a need to descale and flush the system. There are proprietary descalers available for systems with copper and aluminium boilers.ALWAYS FOLLOW THE INSTRUCTIONS. Try SCREWFIX 43140 (£12.29), or 51463 (£13.99).

• Never run your central heating system without an inhibitor. To tell if you have enough, take a jar with a screw lid, and fill it with some water from the header tank. Put some steel or iron nails in the jar, and screw the lid tight. If the nails start to rust after 2 weeks, you do not have enough in your system. The presence of a good quality inhibitor prevents the corrosion and rusting of your radiators form the inside, and in so doing stops the production of gases that require bleeding. It also acts as a lubricant for the pump, helping to increase its life. Try the SCREWFIX site for various inhibitors (e.g. FERNOX MB1 97287, or SENTINEL X100 79683)

• Check the position of your hot water tank thermostat on a regular basis. These can get knocked out of position, and the dial can get knocked to the wrong temperature. Somewhere between 50 and 60 degrees is OK. I settle for 55 on mine.

• Likewise, check the thermostat on the BOILER occasionally. You usually do not need it set as high in summer as in the winter. If it is left up too high, always circulating around the hot water circuit only (a short run of pipe), it tends to “kettle” a bit, before the boiler thermostat cuts in. That is, they sometimes make a noise like a kettle coming to the boil.

• If fitting TRV’s (Thermostatic Radiator Valves), avoid fitting too many, unless you have AUTOMATIC BYPASS VALVES fitted to your system, that can cope with many valves shutting off the radiator flow if they are turned too low. Also avoid fitting one in the area where the room thermostat is, otherwise it may be running all the other radiators too warm, if that TRV is set too low. A good plan is to only fit them in bedrooms, and en-suite rooms that might get too warm. Aim for no more than 50% of radiators in any major zone or loop (i.e. upstairs or downstairs), unless you are going to fit an ABV.

• To check your BTU (heat output) requirements if you need to change or add radiators to your system, try this very useful site link: http://www.theradiatorcompany.com/heatoutput/

• To make draining radiators easier, try this neat DRAINEASY kit made by WALDCO. See: http://www.waldco.co.uk/instructions.htm The main home page shows current stockists: http://www.waldco.co.uk NOTE: if you have a towel radiator with vertical valves, this kit will avoid having to drain down your system, and allow draining JUST the radiator itself, without any mess! A great idea.

Hongfeng Sun : 10 May 2007 16:55 |  Tags: Diy Life |  Comments (0) |  Close comments |  Report a problem

how to set the boiler pressure

There are two valves connected to the flexible pipe.
Turn one value to open position. Turn the other one slowly and check the pressure. Once done, turn both valves to close position.

BTW: Get boiler serviced today and the life of boiler is about 15 years

Hongfeng Sun : 10 May 2007 15:27 |  Tags: Diy Life |  Comments (0) |  Close comments |  Report a problem