Frequently Asked Questions About Condensing Boilers

1. Aren’t condensing boilers just unreliable new technology?

Condensing boilers have now been in use for over 20 years and are extremely reliable – in fact most of the components are also used in non-condensing boilers.

2. Are they only efficient when condensing?

Condensing boilers will ALWAYS be more efficient than a new regular boiler whether or not they are in condensing mode. They can be up to 10-15% more efficient than a modern conventional boiler and up to 30% more efficient than older boilers, so the savings in energy and fuel bills can be significant.

3. Don’t I need to have oversized radiators?

There is only a marginal benefit from using oversized radiators. Larger radiators will allow slightly cooler water to return to the boiler and can increase the efficiency by a further 3%, however, this is not considered to be cost effective and is often impractical.

4. Can condensing boilers be fitted to existing systems?

Yes, they can be fitted to most new and old systems. Normal good practice must be followed, which will include power flushing of the system and the addition of an inhibitor. As with any replacement boiler, an assessment of the effectiveness of the control system and the type of hot water cylinder should also be made.

5. Aren't they more complex and difficult to service?

All condensing boilers installed by us have been manufactured using industry standard parts and are no more complex than a modern conventional boiler.

6. Are there special installation requirements?

They only need one additional installation requirement, which is a pipe to drain away the condensate. This can be into any of the existing waste water outlets in the property or even into its own mini soak-away.

7. Do you need complicated system controls?

The minimum standard for any domestic installation is a room thermostat, an electric valve, and if a hot water cylinder is needed, a cylinder thermostat. This will be fine for a condensing boiler too. You can also have Thermostatic Radiator Thermostats (TRVs), but if they are on every radiator a bypass must be fitted.

8. Is the condensed liquid a problem and is it toxic?

Up to 1 litre of condensed water per hour is produced. This has a pH of about 5, which is between rain water and cola. The condensed liquid is disposed of through a condense pipe connected to the drainage system.

9. What about plumbing from the flue?

The flue gases produced on non-condensing boilers cannot be seen due to their high temperature, but the cooler flue gases from a condensing boiler produce a plume which can be seen. For this reason, care should be taken in locating any flue terminal to avoid the visible plume being a nuisance to neighbours, however, numerous flue options are available.

10. Do condensing flue products kill plants?

The complete opposite is true - plants thrive on carbon dioxide!

11. I've heard there's a limited availability of condensing boilers?

Rest assured, 3 Counties Heating supply a full range including condensing combination boilers.

12. Aren't they more expensive?

The initial cost is higher as condensing boilers have a larger, more efficient heat exchanger than traditional boilers. However, this price difference has continued to reduce and is offset by the saving in your monthly fuel bills due their efficiency. The price difference can be recovered in as little as two years.

For more information on condensing boilers, please see our page on Condensing Boilers or visit SEDBUK (Seasonal Efficiency of Domestic Boilers in the UK) for some useful facts and figures.

13. What areas do you cover?

We provide Central Heating and Plumbing services in:

Hertfordshire: Abbots Langley, Baldock, Barnet, Berkhamsted, Bishops Stortford, Borehamwood, Bovingdon, Broxbourne, Cheshunt, Colney Heath, Elstree, Enfield, Essendon, Harpenden, Hatfield, Hemel Hempstead, Hertford, Hitchin, Hoddesdon, Kings Langley, Letchworth, London Colney, Markyate, Radlett, Redbourn, Rickmansworth, Sandridge, Sawbridgeworth, St Albans, Stevenage, Tring, Ware, Watford, Welwyn, Welwyn Garden City and Wheathampstead.

Bedfordshire: Ampthill, Arlesey, Bedford, Biggleswade, Dunstable, Flitwick, Henlow, Houghton Regis, Kempston, Leighton Buzzard, Luton, Shefford, Toddington and Woburn.

Buckinghamshire: Amersham, Aston Clinton, Aylesbury, Beaconsfield, Bletchley, Buckingham, The Chalfonts, Chesham, Dagnall, Denham, Gerrards Cross, Great Missenden, High Wycombe, Marlow, Milton Keynes, Newport Pagnell, Princes Risborough, Slough, Uxbridge, Wendover and West Wycombe.