Generator for power cuts - water tank pump and ceiling fans

[simon43]

The number of power outages in my locality has increased over the years, despite residing within spitting distance of the international airport.

Usually these outages are short-term, less than a few hours.

However, they have an impact on my guesthouse business - guests are left without air-con and (more importantly), without running water, because the water storage tank is located at ground level and uses a Hitachi on-demand pump to supply water to all bathrooms.

Without water for shower or toilet, guests start complaining very quickly!

Yes, I could build a water tower and provide gravity-fed water during power outages. But the construction cost would probably be more than the cost of a generator.

So, how to provide emergency power to my guest rooms during power outages?

I understand that it will not be possible to power the air-con and shower instant water heaters from a genny.

What I would like to do is to power the room ceiling fans and - most importantly - the water tank pump.

The pump motor is rated at 300 watts.

I'm not sure of the power rating of a ceiling fan - Google suggests a maximum of 75 watts.

Emergency lighting can be battery-powered during the outage.

I have 8 ceiling fans = 8 * 75 = 600 watts, plus the water pump = 900 watts.

I want to know if a water pump has a power surge when it starts, because I need to know what power rating of genny to buy.

Is it important to purchase a pure sine wave AC genny? I think not, if it is only powering the water pump and ceiling fans.

Advice appreciated.

[bankruatsteve]

You should measure the actual power draw of your pump. The watt rating for pumps relates to the water "head" - not the electric. For example, my "250 W" pump draws just under 4 amp while running and probably twice that starting up.

Edit: FYI - I have a 2KVA genset that can handle all the lights, fans, and fridge no problem. When the water pump is used, it growls a bit at start and then operates at higher throttle but no issues otherwise.

[Naam]

I understand that it will not be possible to power the air-con and shower instant water heaters from a genny.

says who?

[robblok]

I understand that it will not be possible to power the air-con and shower instant water heaters from a genny.

says who?

Depends on the size of the generator i guess. No expert here but if entire hospitals can be powered from a generator im sure a guesthouse can too.

[simon43]

I understand that it will not be possible to power the air-con and shower instant water heaters from a genny.

says who?

I should clarify my statement - it would not be financially worth my while to purchase a genny capable of supplying sufficient power to run the air-cons/water heaters, when the outages are increasing but still not that common an occurence.

[Crossy]

Forget your water heaters.

List out exactly what you expect to run from the genset including the capacity of aircons, don't forget your freezers and electric kitchen equipment.

Post here and help will be forthcoming

[simon43]

...List out exactly...

Actually, I don't want to use a genny to power the resort during an outage - I only need to power the water pump to ensure running water for showers/flushing the loo.

So my question is more about the starting current of a water pump - I assume there is a power surge and, if so, what rating should my genny be to handle this without stalling?

[metisdead]

A post containing an oversize image messing up the formatting of this page has been removed.

[Crossy]

...List out exactly...

Actually, I don't want to use a genny to power the resort during an outage - I only need to power the water pump to ensure running water for showers/flushing the loo.

So my question is more about the starting current of a water pump - I assume there is a power surge and, if so, what rating should my genny be to handle this without stalling?

OK, so how big is your water pump? Is it an inverter type? Bore pump? Single or 3-phase?

This site may be of help http://www.submersibleborepumps.com.au/generator_size_for_pump.html

A genset big enough to start your pump will have enough oomph to run fans, lights and your IT infrastructure (guests with lights and internet are happy guests), a bit of re-wiring will be needed so only the essentials switch over when the genset starts.

[Lampang2]

If it's just the pump, change to a 12V pump and run of car battery bank on constant charge from ac network.

The rest would need a generator with automatic start / stop / switching.

More expensive / complicated.

[BHW]

Hi

Have you thought about solar power either to generate electricity or pump water or both, if interested PM me.

Regards

BHW

[simon43]

OK, so how big is your water pump? Is it an inverter type? Bore pump? Single or 3-phase?

As I mentioned in my OP, I am talking about the pump that supplies water from my ground-mounted holding tank, not the pump that pumps water from my well. (I don't need to power the latter because the water holding tank is always maintained at full capacity with a float switch, and its 2,000 litres should outlast the short power outage).

The water tank pump is a single-phase Hitachi pump, GX series, model WM-P, 300 GK-2, rated at 300 watts, according to the label.

Rewiring will be minimal, because when I wired the hotel during construction, I considered the possible future use of a genny, and wired certain circuits separately for this reason.

Automatic genny start and switchover when an outage occurs is not needed - I will manually switch over the circuits that can be powered from the genny. As Crossy states, it should be fine to run my wifi router, TVs, satellite boxes etc, but I need to avoid the use of hot water kettles and hairdryers...

[BHW]

Hi Simon

I replied to your latest however something went wrong & i don't think you got it.

DC pumps either submersible or surface single phase they are not packaged like the Hitachi GX series don't have a pressure switch but one could be installed in the pipe work.

As most outages, I think, are at night you would need battery back up, may i suggest you install a solar system with battery back up for the pump, lights, ceiling fans & small other equipment. Solar servers them during the day & charge the batteries for night use if batteries get low the inverter automaticly connects to grid power. It is better for the batteries to get regular use.

You appear to be an electrician or have knowledge of it so it wound not be too difficult to configure the installation to suit your needs.

These are only my thoughts site unseen & no direct contact with you.

We can talk more if you wish to. My direct email is ; [email protected]

Regards

Bruce

[KhunBENQ]

Have you thought to add some big pressure tank after your pump which is seemingly without?

Such a pressure tank could bridge some time until the generator jumps in.

It is also a relief for the pump with less switching cycles, more steady operation.

May increase pump lifetime and decrease power consumption.

[Gonsalviz]

I run a huge field submersible pump, a pump to the house 3 aircons and ceiling fans, lighting 2 reefers, etc on a 5000 watt genset I paid 25000 Baht for. My guess is you don't need one that big but it might come in handy for a shower if it is a small wall unit.

[Gary A]

I have isolated a 10 amp breaker and put it on a double pole double throw switch. My 2,500 watt generator powers the refrigerator, TV and all the lights. The household water pump is on another circuit but the pump has a regular plug so I can plug it directly into the generator. The little generator handles the 10 amp breaker and the water pump with no problems. Your water pump is bigger than mine so the start surge along with everything else may be too much for a 2,500 watt generator. A 5,000 watt generator would handle what you want with no problem as long as the air cons are shut off. The 5,000 watt doesn't cost that much more than the 2,500 watt.

The double throw switch makes the whole system safe even from my wife.

[IMHO]

A 5kVA gasoline genset only costs 16-18K Baht, and that gives you a lot of overhead... sure they're a little noisy, but if you locate it away from doors/windows and corner it in, it's liveable. The popular cheap ones in TH (Kwaithong/Polo) use cloned 389cc engines, so very easy to get parts and service.

That would run fans, lights, your pump, and one or two AC's in your "presidential suites"

Solar / UPS cannot compete with this, unless you need it for hours every night.