evohome boiler cycles

[dhep72]

Hi all just gat a evohome and 10 rad valves, what is the best setting for boiler cycles have a electric boiler and standard rads,
also this morning one room was calling for heat but the boiler only cut in for about a minute.

[Hot]

Evohome Cycles and mininmum Boiler ON time

Hi all just gat a evohome and 10 rad valves, what is the best setting for boiler cycles have a electric boiler and standard rads,
also this morning one room was calling for heat but the boiler only cut in for about a minute.

Honeywell Evohome has a Cycle Rate of 6 and Minimum boiler on time of 1 minute.

The Cycle Rate specifies how often the boiler will switch on and off in any given hour, measured as Cycles per hour. A typical Cycle rate is 6 cycles per hour giving a 10 minute Cycle length.

A minimum boiler on time for the heat source to dissipate from the system before shutting off. The minimum time is often set to 1 minute.

You can make parameter adjustments on your Central Controller to match the exact requirements of your heating system. These can be found in the Installer Menu.

1. On the Central Controller press and hold ‘Settings’ for 3 seconds
2. Press the green tick
3. Press PARAMETER SETTINGS and choose the parameter you want to adjust:

• Internal Sensor Offset
• Cycle Rate
• Minimum On Time
• Fail Safe
• Optimisation
• Hot Water Parameters

Try using a setting of 3 or 4 cycles and 1 minute as a minimum boiler on time.

Are you experiencing any problems like Electric Boiler Short cycling? You might from time to time (depending on configuration) experience that the boiler only cuts in for about a minute. This could be because of you water pump internal service cycle, which is configured by your electric boiler manufacturer to make sure your water pump does not seize up.

If you are not absolutely sure what you are doing, please ask before you do anything and when you are out of option seek help from professionals like SensibleHeat who are moderators on this site.

[dhep72]

still got a problem one room calls for heat at 5.50am boiler comes on and goes off comes back on goes off again. thought boiler would not start cycling until radiator was at least hot?

[Hot]

Short Cycling

still got a problem one room calls for heat at 5.50am boiler comes on and goes off comes back on goes off again. thought boiler would not start cycling until radiator was at least hot?

dhep72 - I sympathise sincerely with you as there is nothing worse than waking up in the middle of the night and hearing your boiler Short Cycling. Look at what I have suggested and if my advice is not right, please let me know and I will continue to try to come up with the answer you need to solve your problem.

Short Cycling

Boiler short cycling occurs when a boiler subject to its own internal thermostat 'fires up' - starts operating when the thermostat detects that the water in the boiler has cooled down.

For example:

When your heating system does not require the boiler to fire, the heated water in the boiler's heat exchanger will begin to loose heat to the air around the boiler's casing and through the flue. This loss of heat is not related to any loss of heat in your home.
Short cycling is simply the boiler firing up to re-heat the water in it's own heat exchanger when that water has cooled down. Because this water heats up quickly, the temperature that the thermostat is set to is also quickly achieved and when this happens the boiler is again shut down.

The boiler can continue to fire, heating the water in the heat exchanger and shutting down for a prolonged period of time without actually producing any heat for your home.

When the boiler is running and not producing heat for your heating system this 'short cycling' is:

• Wasting energy - increasing your fuel bill;
• Damaging to the boiler's heat exchanger from constant localized boiling;

An essential part of a modern efficient central heating system is the prevention of boiler short cycling.

Preventing Short Cycling

In a fully automatic central heating system the short cycling of the boiler can be prevented by using the room thermostat/programmer and hot water cylinder thermostat to switch on the electrical supply to the boiler. This wiring arrangement is called a 'boiler interlock', meaning that the boiler can only fire when there is a demand for space heating, and/or for hot water.

A boiler interlock will:

• Protect the life of the boiler;
• Save you money;
• Save energy

[SensibleHeatUK]

Sounds like it could be due to a room setpoint not being low enough over night causing that zone to hit the threshold where it begins to operate at minimum output. Try setting your night setback temperature in that zone a degree or two lower and see if that fixes the problem.

[dhep72]

have tried turning the night set back temp down to 11 and at 5.50am 17.5 but at 6.20 this morning the room was at 12.5 and the rad barely warm and the boiler off

[Fursty Ferret]

Check the binding with the HR92 (delete the zone, hard reset the HR92, then rebind).