Problems

Setting up the entire system in a large property does take some time and finding the most comfortable settings for each zone obviously takes a little bit of experimentation, but once the system is running it generally works well.

The installation instructions recommend fitting the Wireless Boiler / Hot Water Relays at least 30cm from any large metal objects and from each other – this may be a wise precaution, but was not found to be strictly necessary, as can be seen from the location chosen by the central heating fitter in this case (despite being aware of the above recommendation):

One minor gripe is that the Radiator Controllers furthest from the evohome Controller can lose their link to the main controller every now and again. This situation will invariably rectify itself after a little while, but the link can be manually re-established by bringing the main controller up to the offending radiator and then re-binding the two units.

When a particular zone seemed to have a more persistent ‘communication error’ message on the main controller, a call to the very helpful evohome support line did resolve the issue, so this is reassuring for any future problems.

Whilst the evohome Controller is for the most part well designed, one annoyance is that the battery life when off its charging base is rather short at little more than half an hour (Honeywell claim an hour, but this doesn’t seem to be the case).

Finally, it would also be nice if the Radiator Controllers would be available in finishes other than just plain white – they simply do not look right on chrome or many ‘feature’ radiators.

Costs

As those of you who have been following the ‘costs in brackets’ above for the main system components will have gathered by now, Honeywell evohome is by no means a ‘cheap upgrade’ to a central heating system – if we take a typical 3 bedroom house, you would probably be looking at £700 for a full system, excluding fitting for the ‘wired in’ components.

You may be aware that you can pick up a basic Nest system for about £200 (3rd generation), also not including fitting.

That would, however, be missing the point – the Nest Smart Thermostat replaces a current one, so maintains the current ‘whole house = one zone’ scenario. Whilst it can perform some pretty neat tricks by learning the homeowner’s habits, what it can’t do is offer different temperatures at different times in different zones (rooms).

Whilst a Nest (or similar) Smart Thermostat will certainly generate energy / cost savings, these would not be at anything like the level of those achievable from a multi-zone system like evohome.

Honeywell has given estimated cost savings of as high as 40% on current energy usage for heating, but this does, perhaps, seem a triffle over-optimistic. Most people would have some degree of insulation in their houses, are probably already using at least some TRVs on their radiators and may well turn these up and down manually as required.

From experience, and by looking to see what others are saying on-line, it is probably realisitc to expect most households to be able to reduce their heating related energy expenditure by about 20% - 25% p.a. after fitting a complete evohome system.

According to the UK Government report “Average annual domestic gas bills by home and non-home supplier”, the average UK domestic gas bill in 2015 was for £714.

If we assume the vast majority of this was used to provide central heating and hot water (as opposed to cooking and gas fires), then we would be looking at a typical annual saving with an evohome system of say £160, giving a payback period on the purchase cost of a little less than 5 years (ignoring installation costs and battery replacement for non-mains powered components).

However, the vast majority of homeowners choosing to install an evohome system are not doing so just to save money – the flexibility in control, increased comfort and intregration with other ‘Smart’ systems would all be important considerations and the incrememtal cost if building evohome control into a new central heating system would be much, much lower (as you would typically need to buy conventional control components for such a system anyway).

So, having considered all aspects of the installation and usage of a Honeywell evohome system, is it the best 'Smart' home heating control system on the market? Here is our verdict...

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The installation instructions recommend fitting the Wireless Boiler / Hot Water Relays at least 30cm from any large metal objects and from each other – this may be a wise precaution, but was not found to be strictly necessary, as can be seen from the location chosen by the central heating fitter in this case (despite being aware of the above recommendation):

One minor gripe is that the Radiator Controllers furthest from the evohome Controller can lose their link to the main controller every now and again. This situation will invariably rectify itself after a little while, but the link can be manually re-established by bringing the main controller up to the offending radiator and then re-binding the two units.

When a particular zone seemed to have a more persistent ‘communication error’ message on the main controller, a call to the very helpful evohome support line did resolve the issue, so this is reassuring for any future problems.

Whilst the evohome Controller is for the most part well designed, one annoyance is that the battery life when off its charging base is rather short at little more than half an hour (Honeywell claim an hour, but this doesn’t seem to be the case).

Finally, it would also be nice if the Radiator Controllers would be available in finishes other than just plain white – they simply do not look right on chrome or many ‘feature’ radiators.

TechReport (UK)