Building Construction, Renovation, Maintenance & Advice

Large Versus Small Hot Water and AC Systems

"Taming The Beast"


The cantankerous, character building nature of hotel air conditioning and plumbing systems.

I am sure you know the feeling well.

A special occasion has come up. You decide to take your beloved for a weekend away. You book into a hotel. You want a hotel with a bit of character so you avoid those toytown modern creations and go for something more up market and with a bit of character to it. Character? Did I say a building with character or character building?

You enter the room, there is that inevitable Indonesian hotel marketing feature of the acrid smell of stale tobacco smoke coughed up from the lungs of hundreds of emphysema ravaged persons which has permeated the room and everything in it. The cigarette burn on the edge of the cabinet says it all.

The room is cold, very cold, somehow in this country luxury means colder than an eskimo’s buttocks. You hunt for the control, a strange and not very confidence building sliding device on the wall. You slide it, nothing happens, you slide it the other way still nothing happens. The rush of cold air is as controllable as a schizophrenic rhinoceros on a lead. In desperation you have another go ……… a sense of inevitability creeps through you as the slider comes off in your hand.

Eventually you climb into bed and, pulling the single sheet up over your head to keep the frostbite away and drown out the incessant drumming of some hidden and uncontrollable fan, you fall into a deep sleep……

You start dreaming of falling into an icy river and gasping for breath and, shivering, you wake up - the water and ice are gone but you are still shivering. You rummage desperately through your suitcase trying to find something warm to put on and, with 5 tee shirts and a bath towel wrapped around you, you climb back into bed.

Eventually the grey hue of morning comes and you wake from a disturbed sleep feeling like a bus load of sumo wrestlers ran over your head. You yearn for a refreshing shower to try and restart your day. You hop into the bath and turn on the shower - cold water. You wait for a while and slowly the water heats up a smidgeon to “almost barely luke warm” on the hotel bathroom temperature scale. You adjust the temperature and manage to achieve “not quite luke warm but getting fairly close” but then, just as you launch yourself under the flow, it turns to “cold as a polar bear’s ears”. How did it do that? You look around nervously for the sensor that told the plumbing system the exact time to sabotage you. You turn down the cold tap and the water warms a little but then the flow peters out to a mere dribble. Nothing you try works, there is no hot water and your mind inevitably wanders to some smug bar steward in another room who stole your water and is enjoying a nice hot shower. You suppress a burning desire to run down the corridor banging on the room doors shouting “give me back my hot water you selfish swine, I hope it scalds your nuts off.”

But then suddenly your cogitation is broken as the hot water returns with a scalding element of surprise. Cursing you jump out from under the shower your feet slithering around on the curved surfaces of the bath. Stretching to avoid the water you adjust the temperature by adding some cold and once again you slide gingerly under the flow. But then, with a cough and a belch, some distant knocking and finally that familiar sound of the flatulent cow of doom, the flow dries up leaving you with a dribble not even strong enough to struggle its weary way up to the shower head.

You look around for a solution and in desperation you grab the waste bin and pulling out the bin liner, you fill it with cold water from the sink and start hysterically pouring it over your head……..

The cantankerous, character building nature of hotel air conditioning and plumbing is legendary and behind the scenes hotel engineers have, for generations, struggled through long days and even longer nights wresting with a beast they can neither understand nor tame. The older a hotel gets the more cantankerous its systems become.

If you are ever brave enough to venture into the bowels of a large ageing hotel you will find a veritable dog’s breakfast of systems that have been modified and modified and modified again over eons (there’s that word again) of time by frustrated Artisans who have run out of art long ago leaving nothing but the sans (look it up in a french dictionary).

Hotels tend to use large systems

Hotels for some strange reason think big. Perhaps at the design stage some bored engineer starts to wet his pants with excitement at the thought of designing some mammoth complex engineering masterpiece.

Many hotels use large centralised systems for air conditioning, water supply and water heating. We must assume that the reason is for greater efficiency and therefore lower cost but is this really the case?

These large systems must keep running regardless of how many or how few people are in the building. They may be fine for a factory with large open spaces or in an office building where rooms are nearly always occupied through the day but in a hotel where occupancy fluctuates there are great advantages in only cooling and providing hot water to the spaces that are occupied.

These large centralised systems present a major challenge in terms of control at the local (individual room) level.

Large air conditioning systems distribute air by sending cold air down long networks of ducting. Delivering the right amount of air at the right temperature can be very difficult particularly when you consider that some rooms are close to the air conditioner while others are 25 million miles away.

Similarly problems occur with hot water systems. Corridors can be very long and, once again, some rooms may be fairly close to the water heater while other rooms may be a long way away and it may take several minutes for the hot water to get to bathrooms in the nether regions. To solve this problem large hotels often use recirculating hot water systems. A circulation pipe carries the hot water from a large centralised heater around the rooms and back to the heater. A pump keeps the hot water continuously circulating so that there is always hot water in the pipe as it passes close to each bathroom and (theoretically) if you turn a hot tap on you will always get instant hot water.

All very well in theory but we all know that theory and practice are often two totally different things. This arrangement has several problems. The first is that the hotel is continuously heating water even if it is not being used or, at times of low occupancy only a small amount is being used, this is expensive. Secondly the reality is that one heater is supplying hot water in varying amounts to many bathrooms, some near and some far away through a single pipe. Inevitably the people in the furthest bathrooms are likely to be the last in the queue for hot water and the pressure in the pipe is going to vary as people all along the way turn their showers on and off. This is why there are fluctuations both in the pressure and temperature of the water you receive in your bathroom.

Multiple small systems are easier to maintain and provide individual control

A far better approach that is becoming more popular these days is to have small independent systems for each room. You will note that many hotels these days are starting to install individual air conditioning units for each room.

This approach can also be applied to plumbing services with small individual pressure pumps and water heaters to supply the bathrooms. A large bore pipe delivers cold low pressure water to the rooms. At each bathroom a small individual pump draws water from the supply pipe and feeds it to the bathroom thereby providing stable water pressure that is independent of the rest of the system. Each bathroom also has its own water heater thereby guaranteeing hot water regardless of what is happening in the rest of the hotel. Water is only heated when the room is occupied and only pressurised when it is being used.

In addition if the hotel has independent air conditioners and water heaters for the rooms a further step can be taken and that is to provide an air conditioner water heater with an electric booster element on a timer for each bathroom. These units are only a little more expensive to buy than a standard electric water heater and provide free hot water. Hot water bills in a hotel can be a very expensive item in the budget.

Advantages of small systems in hotels

The use of small independent systems can provide a number of advantages:

  • They use standard mass produced air conditioners, water heaters and pumps and so are not expensive to install.

  • If a unit fails only one room is put our of action.

  • Customers have far greater control over the room temperature and the pressure and temperature of the water in the bathroom.

  • You don’t need a highly trained engineer to continuously manage a complex system.

  • Operating costs reduce proportionally when occupancy rates are low.

  • You save the cost of continually maintaining pressure and heat in the system whether people are using it or not.

These principles may also apply to small villa developments and ordinary houses particularly if they have more than one floor or there are long distances between buildings. If some profit minded individual wishes to sell you a more expensive pump and provides you with something large enough to irrigate the Sahara Desert you are left with the problem of trying to tame the beast. A design that breaks down your systems into small independently managed services may well provide you with a more effective system.

So next time you are hopping around on one leg in some supposedly five star hotel bathroom and the water has spluttered to a freezing halt you might decide that there really is no excuse for this and, rather than running around the corridors abusing everyone you meet, you might consider venting your spleen with a letter to the hotel management company.

Copyright © Phil Wilson 2013
This article or any part of it cannot be copied or reproduced without permission from the copyright owner.

9 December 2017 Copyright © Mr Fixit,
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