What next? High electricity usage.

debitcardmayhem

Sadly I cant find what the power rating of the pump, someone else may know ,  my guess is circa 75W

QrizB

Debdon said:

The combi boiler we have is the
 Greenstar 30i which I think has a pump 30kw

A boiler circulation pump is rarely more than 200 watts. It'll run whenever your central heating is on, but shouldn't be involved in delivering hot water - that's supplied at mains pressure.

Unless you're in a low water pressure area and your house has a booster pump?

Scot_39

The 30kW will be the effective peak gas power - the actual heat.

GCH pumps for radiators are relatively small - power - far more like 30-40W - and that only when radiators running.

The hot water - in a combi - is normally driven purely by mains pressure.  

Some use power showers - with their own small impeller pumps - these can be integrated into electrical showers - or they can be purely flow boosting pumps feeding thermostatic mixers  in low pressure homes (e.g. loft gravity fed tanks) - checking a few - those were around the 200-250W 

Cold fed electric showers range from typically 8.5 -11.5+ kWh for the actual water heating.  A 10 min shower - 1.5kWh for my 9kW model - or about 40p at current single rate.

doodling

Hi,

The (current) specs for the Greestar 30i state a maximum consumption of 127W (electrical) when running.  I would expect that it would be near to this when supplying hot water as the boiler will be running at near full power with both fan and pump running near maximum speed.

The pump does run when a combi is supplying hot water.  The hot water is heated from the CH water via a secondary heat exchanger, the CH water being heated by the main flame/water heat exchanger and the pump running to circulate the water between them.

127W is not a significant amount of electrical power so unless you're having really (really!) long showers then it won't be a significant factor in your electrical electricity consumption.

FreeBear

doodling said: The (current) specs for the Greestar 30i state a maximum consumption of 127W (electrical) when running.  I would expect that it would be near to this when supplying hot water as the boiler will be running at near full power with both fan and pump running near maximum speed.

During the winter months, my boiler (Viessmann 050 combi) will be running flat out when heating water. This time of year, it drops down to around 50% of full capacity. Maybe consuming 70-100W electricity in the process. Running 10 mins for a bath or even 30 mins for a shower isn't going to add much to the electricity bill.