Perfect Heating And Plumbing's Guide to Central Heating Problems

How much will it cost to have a new boiler installed?

Every heating installation is different. So to make sure that the right boiler is selected you need to arrange for an engineer to visit. Generally these visit are conducted in the evening, so that you don't have to take time off work. During the visit your existing heating controls will be visually inspected and you will be advised upon the best way to make them comply to current Regulations. After the visit you will receive a free detailed quotation, not an estimate, which is specific to your requirement.

Call 07802 758166 today to arrange an appointment.

What is a SEDBUK rating?

The SEDBUK (Seasonal Efficiency of Domestic Boilers in the UK) rating was developed under the governments Energy Efficiency Best Practice Programme to provide a fair comparison of different models of boilers and is a measure of the average annual efficiency under typical operating conditions.

BAND	SEDBUK RANGE
A	Above 90%
B	86-90%
C	82-86%
D	78-82%
E	74-78%
F	70-74%
G	Below 70%

Changes to the Building Regulations for England and Wales (part L1) which came into effect on 1st April 2002 to help reduce the United Kingdom's production of carbon dioxide, require domestic boilers fitted to new buildings to have a SEDBUK rating of A to D. Non-compliant boilers may be fitted into existing buildings until 31st August 2002.

The use of Cleaner to commission new systems followed by treatment with System Inhibitor will ensure that the efficiency rating is maintained.

Why are some of my radiators hotter than others?

This usually means that your central heating system is incorrectly balanced. This is both inefficient and effect your comfort. An engineer will be able to re-balance your system and suggest any other improvements.

My combination boiler produces a poor flow of hot water?

Older combination boilers often have a poor flow rate compared to newer models. This is due to design and age of your boiler. The problem can be made worse over time by lime scale build up inside the boilers heat exchanger. It is recommended that you arrange for an engineer to call.

Call 07802 758166 today to arrange an appointment.

Why do my radiators not get hot to the touch?

Check that your boilers thermostat to set to maximum and that your room thermostat is set to a minimum of 20.

Why are some of my radiators hot at the top and cold at the bottom?

This in normally do to sludge build up in the bottom of the radiator. This can be removed by powerflushing the entire heating system. However the cause of the sludge should be identified , for example you may have a leak, your system may be "over pumping" or you may not have a lid upon you central heating make-up cistern. These can be easily rectified by an engineer. Please read about powerflushing within the Heating & Boiler section.

Why are some of my radiators cold at the top and hot at the bottom?

This is normally due to air being trapped in the top of the radiator. The air can be released by using a radiator key. Be very careful when releasing the vent screw that you don't unwind it to far so that it falls out. Also when re-tightening the vent screw only do it up finger tight so that you do not break the vent screw off inside the radiator.

My Feed & Expansion tank contains 'foulant'. Will System Inhibitor remove this?

System Inhibitor is a mild biocide, but if your feed and expansion tank is contaminated with a jelly-like substance that smells (which could be bacteria, algae, fungal growth or yeast formation) then you should bail out the tank and rinse with a 10% solution of household bleach. Observe good personal hygiene practice.

The expansion of warm water into the feed and expansion tank, together with the ventilated loft space means that the ideal environment has been provided for airborne bacteria and spores to thrive.

Although one might expect the natural 'pasteurization' effect (15-30 minutes at 60°C) within an active central heating system to kill off these bugs, their effect on water quality can be detrimental. Its therefore important to remove this contamination.

Organic matter in their metabolism produce change in the composition of water; algae remove carbon dioxide and give off oxygen while other organisms consume oxygen. Decay of organic matter may also generate corrosive amino-acids.

Sulphite Reducing Bacteria (SRB's) for example which produce hydrogen sulphide cause corrosion directly but are only active during periods of inactivity. (Over the summer for example). There are, however, mesophillic and thermophillic SRB's which can survive and grow in hot water.

Treating a clean system with System Inhibitor and covering the feed and expansion tank with a close fitting lid should prevent reoccurrence of the contamination.

Does my water quality affect my central heating system?

In a word, YES! Hard water tends to be scale forming, whereas soft water tends to be corrosive. Either way, an inhibitor is beneficial.

Levels of calcium and magnesium in the domestic supply vary throughout the country. There is no UK maximum limit for hardness. Higher levels of hardness will be found in areas where rain-water percolates through limestone rock. Granite or surface water supplies will tend to be softer.

If white deposits form on your kettle element, or white scum floats in the bath, these are indicators of scale. Heating causes dissolved bicarbonates to form solid carbonate limescale and is more likely to happen when temperatures exceed 60°C. A simple test can be carried out with vinegar. Scale will fizz slightly and give off bubbles.

Because your central heating system re-circulates the same water, there is little opportunity for new hardness salts to enter the system, unless you have a leak! Unfortunately the small amount of hardness will tend to deposit itself on the hottest part of the system, resulting in irritating noises.

Hardness is measured in parts per million (ppm) of calcium carbonate (CaCO₃). See table below for the description of hardness levels:

Description	Hardness ppm
Soft	0 - 50
Moderately Soft	50 - 100
Slightly Hard	100 - 150
Moderately Hard	150 - 200
Hard	200 - 300
Very Hard	300+

In soft water areas the installation of System Inhibitor will protect the metals from the corrosive nature of the water and in hard water areas, the scale inhibitor within System Inhibitor will control hardness. In very hard areas it is recommended to additionally install System Silencer.

My pipes creak and tick

If the noise emanates from under the floor or within the walls, away from the boiler, then the most likely cause will be that the pipe's free movement has been constrained and the noise is thermal stress. (Radiators may also be heard to creak in their brackets).

Pipes expand when hot and contract as they cool.

For example, each 1-metre length of copper pipe-run will increase axially by 1 millimetre over a 60°C temperature gradient.

Adding treatment chemicals will not break the laws of physics!

If you wish to eliminate the noise then you have little choice but to lift the floorboards or break into the wall and make provision for movement. Pipes that run parallel to joists should be secured with clips that allow movement whereas pipes that run across joists should sit in large enough notches to accommodate felt lagging to cushion against rubbing.

Alternatively you might consider adjusting your programmer so that your system comes up to temperature (and cools) at times during the day when the creaking noises will be less obtrusive.

Humming noises usually emanate from the circulator pump. Vibration noises of this type can be caused by an ineffectual mounting bracket or wear to the impellor shaft/bearing.

What is Benchmark?

Benchmark is an initiative launched to improve quality within the heating industry. All competent heating installers should be aware of benchmark standards. Virtually every boiler sold in the UK comes with its own log book which should be fully completed by the installer and handed to you once your new boiler has been installed and commissioned. This log book becomes your certificate of compliance with all relevant building regulations and also is your guarantee. No certificate no guarantee.