There are 3 types of boiler whether it is Gas or Oil, condensing or not.

• Combi
• System
• Regular (or Conventional)

A combination boiler is very popular in the UK and accounts for over 1/2 of all boilers fitted. The main difference between a combi and any other type is that you do not have to store hot water.

It is in effect a (Combination) of a water heater and a central heating boiler. You do not need a hot water cylinder/tank or a cold water tank in the attic.

Another benefit is that hot water is delivered to your taps and shower at mains pressure (assuming the pressure is good). However it is a common mistake to think that a combi will do all. You should choose either system or regular boilers if you have poor mains pressure or multiple taps & showers.

A typical regular system will incorporate a boiler, controls, a feed & expansion tank, a cold water tank and a hot water cylinder/tank.

This is the system that most UK households will currently have.

The hot water is normally on a timer and the cold water is via the roof tank. You can replace an old or faulty regular boiler with a new condensing regular boiler.

A system boiler is similar to the regular boiler in that is uses the hot water cylinder. However many of the components are housed within the boiler saving space & money.

This is the best option if you are wanting an unvented cylinder.

A condensing boiler is a high-efficiency boiler which condensates from within the heat exchanger.This is then discharged via a plastic drain pipe to the outside. Much of the heat produced in the combustion process is absorbed into the heat exchanger instead of going up the flue as before, hence less fuel is burned.

From the 1st of April 2005, the government brought in new regulations concerning the fitting and specification of Gas & Oil boilers. This they did in an effort to reduce the amount of Carbon Dioxide discharged through boiler flues and to lessen the effect of these gases on the environment.

The new regulations mean that all boilers (Gas) fitted in new build and most replacement have to be condensing SEDBUK rated A or B. SEDBUK means a boilers efficiency rating of over 86%.

In April 2007 it is expected that a ruling stating all Oil boilers fitted should be condensing too.

All Gas boilers must be fitted by a CORGI approved installer and Oil boilers by a OFTEC registered engineer.

Every boiler manufacturer has different lengths to which their vertical and horizontal flues can reach. There will be a maximum either way.

After you have chosen a boiler, submit what length flue run you want to achieve via our Ask Bob contact section and we will get back to you with the answers.

Alternatively visit the manufacturers website found on the opening page of which boiler you have chosen.

A TRV (Thermostatic Radiator Valve) allows you to control the temperature of the room by turning the head to different settings.

They must be fitted in all new systems and also if you are replacing radiators, according to Building Regs Part L.

An OFTEC registered engineer is required to fit any oil tank.

To find a local OFTEC installer please click here.

1 bar pressure is equivalent to 33ft head of pressure or 14.5 psi.

A very good pressure for a twin impeller pump is 3 bar plus.

• Gravity Fed Hot & Cold
• Gravity Fed Hot & Pumped Cold
• Unvented Mains Pressure Systems
• Combi Boilers

The High Pressure Mixer has a minimum & maximum working pressure of between 0.5 bar and 5 bar and is capable of delivering up to 18 litres/Minute.

The Pumped Mixer has a minimum & maximum working pressure of between 0.01 bar and 1 bar and is capable of delivering up to 16 litres/Minute.

Electric Showers are straight from the mains cold and heat via an electric element within the shower. They can be as much as 10.8kw and therefore you should check your mains fuseboard or similar to see if you have the capacity to accept a further load. You also must not attempt to wire the shower if you are not part 'P' self regulated (ie, an electrician).

Mixer showers are as the title suggests a mix of the hot water from the cylinder and the cold from the cold water tank. A thermostatic shower will allow for changes in temperature and pressure due to perhaps a bath tap or washing  machine being turned on, whereas a manual mixer will not.

Power showers fall into 2 categories  - A mixer valve with a added twin impeller pump to boost a hot and cold feed to up to 4 bar, and also a power shower with an internal small pump within the unit to boost the pressure.

If you have either a combi boiler or unvented system a mixer shower will work well off of either.

NB: Power showers CANNOT be used with these types of systems.

Kilowatts is metric, Btus is imperial. You can convert either by using the following conversion:

Btus into Kilowatts - multiply by 0.0002931, eg. 105,000 Btus x 0.0002931 = 30.78 Kilowatts

Kilowatts into Btus - multiply by 3412, eg. 30kw x 3412 = 102,360 Btus

Here are some other handy conversions you may need.

Feet - Metres - Multiply by 0.3048
Metres - Feet - Multiply by 3.281
Inches - Milimetres - Multiply by 25.4
Milimetres - Inches - Multiply by 0.03937
Gallons - Litres - Multiply by 4.546
Litres - Gallons - Multiply by 0.22

No, unless you are Part 'P' self-regulated or an NIC/EIC electrician.

If you are not Part 'P' self-regulated or an NIC/EIC electrician, , you cannot, and should not, attempt any wiring on showers or boiler controls, or anything to do with electricity.

Take the following into consideration when choosing between copper and plastic:

Price: 15mm copper £2.05/mtr, 15mm plastic £0.90/mtr (prices correct at time of writing - please check the Plumbing & Sundries section for up to date pricing)

Saving on materials: No gas, solder, soldering mat, flux, etc.

Corrosion in copper - Hep2o has a 50 year guarantee!

Less fittings required: The pipe can be used similarly to cable as in it can be pulled through joists for example, saving on joints every few metres or so.

Time: Push the fitting on with the insert in the pipe and thats it!!

Why use plastic plumbing you ask??!!