Eberspacher high/low cycling

[Mitchellmoxo]

Hello,

 

My eberspacher will run for about 10 mins on high power cycle and then switch between high/low power about every minute I understand this is because it has reached its temperature and goes into a lower power mode.

 

After reading about these units I understand this is no good for the heater but how do I go about sorting this? There are TRVs on 2 of the 3 radiators but are always set to max 5 so would it make a difference if I change these to normal radiators valves? Or is there anything else I can do?

 

It is worth saying that there isn't anything wrong with the eberspacher at present it is doing exactly as it should (heating up rads and hot water tank) but it constantly going from high-low power modes makes me think this cause an issue in the future.

 

Regards

Mitch

[cuthound]

Sounds like there is not enough load to take the heat output of the Ebersplutter.

 

Removing the TRV's will help, but may not be enough. Might be better to fit one or more radiators.

 

Edited for smelling.

Edited May 21, 2016 by cuthound

[Roger Crown]

It could be short cycling through the calorifier loop, depends how it is plumbed.

 

Roger

[NMEA]

Three radiators (unless the are about 2kw each which seems unlikely) is not nearly enough, evaporator heaters should be loaded to boiler kw rating + 10% of short cycling is inevitable, the calorifier should be ignored in any calculations and TRVs should not be fitted. Most narrowboats are fitted wit a D5 or a TTC, both of which are 5kw plus, a more appropriate heater is the 4kw model and even then it can be a challenge to load them enough. As I have mentioned ignoring the calorifier I guess I should also give the rationale, whilst cold they are an excellent load but as they warm up the become less and less of a load until coolant and heated water temperatures equalise when they are a virtually zero load. Constant cycling, particularly at the rate you describe will result in more frequent service, though mercifully not nearly so much as it would have before the introduction of ULSD red.

Edited May 21, 2016 by NMEA

[Mitchellmoxo]

thanks for replies, it is the D5 model I have fitted. So apart from adding more radiators is there much I can do as I do not really have the space for an additional radiator?

[cuthound]

Could you possibly add a loop of pipework to act as underfloor heating to increase the heat load?

[NMEA]

thanks for replies, it is the D5 model I have fitted. So apart from adding more radiators is there much I can do as I do not really have the space for an additional radiator?

You could replace the ones you have with type 22 ones of the same height and width if you don't already have those, and or a buffer tank to increase the coolant volume. Aluminium radiators will also disperse heat faster.