Low Power Air-Cons And Other Power-Reducing Tips

[simon43]

Following on from a previous thread about my guesthouse project, I need to understand how I can reduce the maximum current demand in this three-storey property, since it is only supplied with single phase. The three-phase supply is balanced out between the 12 shop houses that are in this block. It could get expensive if I need to run a new electricity supply and will probably make the project financially unrealistic. (For my previous small hotel, I paid to get a dedicated 3-phase supply installed, but I do not really have that option here).

The property would typically need to supply power to:

7 bedroom air-cons + 1 restaurant air-com

7 bathroom water heaters

1 clothes dryer

Sundries - small current demand

Typically, the air-con units would be used between about 5pm - 9am, (since they would be off during the day whilst guests are not present).

The clothes dryer/washing machine can be scheduled to operate during the day, so that doesn't conflict with the air-con operation.

For the bathroom water heaters, I could use solar water heaters, (there is a flat roof to the property). Does anyone have experience of using these types of water heater? How much hot water is available?

So that really leaves the greedy air-con units as the main source of power consumption. I'm not in a position to do much in the way of constructing energy saving walls/ceilings etc etc, because these are already in place.

Apart from the wonderful method raised in another thread about clamping a 'gizmo' onto your meter and reducing your electricity consumption by 50% (!), are there any air-con units which can actually cool the room for a cost that is lower than the norm?

I should add that the bedrooms are quite small, and I have read that one can purchase smaller, 5-amp air-con units that are suitable for cooling up to 150 square feet.

Asking a lot I know, but your advice is much appreciated.

Simon

Edited June 25, 2010 by simon43

[bangkokburning]

Hey, saw your post..good luck. There is always a place for a GH that does it right.

This isn't exactly on topic but I have noticed thru the years that many GHs that start out offering AC throughout often open up the common areas and let the guests deal with it. If you are thinking about AC in common area or cafe.

Many Gh's in Maylasia have cold water. I'm OK with that. Usually it's refreshing.

Do you have some place to hang the wash (roof?) ? Nix the dryer or have one for rainy season only.

Usually B100 is added to rooms to cover the AC per day. This does little to discourage guests from closing the AC when they leave - hence you pay for what you could save AND your energy consumption concerns. Have one of those put the key in and turn everything on things ???

Can you lower the ceiling with plastic tiles and insulate perhaps? Big help I think,

Don't cheap out on he AC, the guests will push it hard to deliver.

If you have room fridge, buy new. Those old fridge suck power like mad.

See what you can do to naturally keep the rooms cool (windows closed/no smoking).

*make sure the rooms hae plenty of outlets. Cheap Chinese GHs often have no or few outlets. Now, with all the electronics gear, having outlets is a draw. No one wants to hang about while their _____ charges in lobby.

Finally - solid lockers in lobby. Plain view w/ CCTV.

[katabeachbum]

7 bathroom heaters is your major problem, 7 x 3,5 kwh = 105 Amp max load/2 =50 amp. Is there any chance of installing hotwaterpipes to the showers? If so I would replace the 7 heaters with a 200liter boiler needing only 2-3kw/10-12 Amp, and cost same as 7 heaters. Connect it to a timer to heat water 3am to sunrise when AC are not working hard + daytime Solarhotwater doesnt get really hot on cloudy days, and early morning shower is icecold.

Size of room and windows exposure to sunshine decides needed size of aircon. I guess Inverter aircons are out of the question due to price, but 9-10 BTU AC at 12-13k baht installed can be sufficient for 15 sqm rooms. Worst case it takes 15 minutes longer to cool down room. Approx 5 Amp each when compressor running. I use 9 BTU in some of my 25 sqm studios with shaded windows/walls and it works fine

i would not aircon restaurant/commonareas. Cost a fortune with doors opening frequently.

If you already have a 15/45Amp single phase, replacing it with 15/45 3-phase would cost approx 6k to electric company and 10-20 k for domestic parts/work. Could be less expensive than installing hotwaterpipes

[simon43]

The bathrooms and bedrooms are not yet constructed, so certainly I could install a main hot water tank on the roof for delivery of hot water to all rooms. This is more akin to the UK system, where an immersion heater is installed to ensure that the water remains hot all the time. Once the water is up to temperature, it's not so expensive to keep it at that temperature if the holding tank is well insulated.

You say a 200 liter boiler, but surely that is only enough for a single guest-room? I will need 200 x 7 liters of hot water.

The bedrooms are about 25 square meters, so the smallest air-con units should be ok. (Which company makes small and reliable air-cons? I only see larger units from the major manufacturers).

Simon

Edited June 25, 2010 by simon43

[katabeachbum]

The bathrooms and bedrooms are not yet constructed, so certainly I could install a main hot water tank on the roof for delivery of hot water to all rooms. This is more akin to the UK system, where an immersion heater is installed to ensure that the water remains hot all the time. Once the water is up to temperature, it's not so expensive to keep it at that temperature if the holding tank is well insulated.

You say a 200 liter boiler, but surely that is only enough for a single guest-room? I will need 200 x 7 liters of hot water.

The bedrooms are about 25 square meters, so the smallest air-con units should be ok. (Which company makes small and reliable air-cons? I only see larger units from the major manufacturers).

Simon

one 200-300 litres hot water tank works fine with 7 baths. I have 200 L Fagor at 19k baht with 2x1100 watt (10 Amp) heater on my roof. Never run out of hotwater for 7 studios, pool rainshower and 2 kitchen. Water temp in is 25-35C and airtemp where tank is installed is 25-40C, and the hotwaterpipes run in warm walls and ceilings, not like in the UK where hotwatertank and pipes heat the rooms. Your max demand was just reduced with 40 Amp:) , and the water can be heated when AC are not working hard. Fagor 300 liters need 15 Amp and is approx 28k baht.

9-13 BTU aircon are inexpensive and reliable from Samsung and LG, check at HomePro. Make sure you look at only energy class 5, but even within those there are differences in powerconsumption. Check the yellow EGAT label on indoorunit. For 25 sqm I would choose 13BTU, since thats usually only 2 Amp each more max demand.

If heating water and dryer is not allowed at the same time, you may manage with 15/45 Amp singlephase meter with a 63 Amp main braker

[elkangorito]

Invest in Solar Hot Water & don't pay a cent for usage. Thailand is the perfect country for Solar Hot Water.

[katabeachbum]

Invest in Solar Hot Water & don't pay a cent for usage. Thailand is the perfect country for Solar Hot Water.

in a guesthouse where everyone takes a shower 6-7pm, solarhotwater is rather cold 6 am. I did a calculation on solarhotwater, and ROI was like 7-10 years compared to 200 liter 2,2 kw tank

[thatguy]

As ElK says, solar works great when it's working. If you go with a rooftop tank, even a homebrew solar panel will give you most of your hot water for very little construction costs. The thermostat will kick in the immersion heater to warm the water for early morning.

tg

[moe666]

How long do you plan on keeping your guest house if a long term investment then solar is a good ideal. Have a system with elect. heater that will boost water temp. for early morning use and those cloudy days. But donot cheap out on system the controls to coordinate between elect. heat when needed and pure solar are crucial. Also if possible install a hot water recirc system that will provide hot water on demand the pump for these systems are small and donot draw a lot of amp. but save on water. The hot water user doesn't have to leave water running for 5 min. to get hot water.

[bangkokburning]

Did you ever consider doing dorm rooms? I can't stand them any more because the kids are so messy and have so much gear and then there is the snoring. But If you might consider, have a look at Inn Crowd in SNG. It's been years since I'd stayed there, but it was packed. AC dorm. Just have lockers, really good idea. Security/safety.

Many young people are quite alright with communal showers and toilets. At 49, I may or may not take a private and it often depends on length of stay.

In regard to water - you can have a look at a bunch of high volume small guesthouses in Penang off Chulia (Munti/Campbell) to see how backpackers roll out of bed and use showers communally. Incidentally, in all 3-4 Ghs they are all cold water. I'd forget the hot water completely unless I was doing this in a place that gets a hard chill.

My 2 baht -

Edited June 27, 2010 by bangkokburning

[bangkokburning]

I have no idea what power consumption is like for those small immersion heaters - but it is VERY difficult to think of places where they use central hot water. All use those little heaters. They are cheap and last forever. Personally, I think a big black tank on the roof is plenty. In fact, it will be too hot in the day. Currently in my gf's flat we get the water from the roof and I have to let it run (wa$te) becasue it is uncomfortably hot. Not even warm - hot.

Your ROI will be hard won. Keep it simple.

[Naam]

As ElK says, solar works great when it's working. If you go with a rooftop tank, even a homebrew solar panel will give you most of your hot water for very little construction costs. The thermostat will kick in the immersion heater to warm the water for early morning.

"immersion heater"?

[harrry]

REmember baths use lots more water and heat than showers.

[Deke]

You might look into those water heaters that use waste heat from the air conditioner to heat the water.

[thatguy]

immersion heater, was the reference used in an earlier post. Generally they screw into the side of an electric water tank. There are often two, upper and lower on larger tanks. 220v in the states, likely same elsewhere. they look like a black loop extending about a foot into the tank. Thermostat controlled.

tg

[Lizard2010]

If you really want to cut your electricity power bill you could invest in a Solar Power System

.

[katabeachbum]

If you really want to cut your electricity power bill you could invest in a Solar Power System

.

so how much saving on a 7 shower guesthouse with 4 x 10 minutes showers a day each shower and cold water in 25C, hotwatershower 38C?

Compared to 200L hotwatertank with 2200 watt heater.

Edit Sorry I misread solarhotwater. Solarpower even more interesting. What kind of investment needed in solarpowerequipment to cover OPs need, and how many sqm of solar space needed to install it?

Edited July 1, 2010 by katabeachbum