Hotel Water Distribution - Pressure Issues

Swap the shower mixer inlet connections over. The issue is one of the temperature controller inside it oscillating from full hot to full cold, because the pipes are connected the wrong way round.

1)Check if the connections are taken before the booster pumps. Need to understand the piping circuit. Generally, booster pumps sucks and hence there will not be any water down the line.

2) Also if the pressure difference in hot and cold water is high, the high pressure will not allow the low pressure and hence the fluctuation.

3) The pressure difference should not be very high

This is happening due to thermostat valve in the mixure assembly. Check the pressure rating of the Mixure assembly in suitable units. PWslack may be correct. You can swap the connections and then check for the problem.

Turn the hot water off.

Get a roof tank...

Absolutely agree. Best way to stabilize water pressure. I will even award you a GA for that.

As a bonus, a large roof tank will dampen building sway. The water in the tank will create an inertia movement opposite to the building movement. Might not be a big problem in a four story building, but it can't hurt (as long as the structure and the water supply system both support it).

[edit] I'm reconsidering... only a four story hotel... won't really get much pressure, maybe 25 psi at the ground level... oh, hell, it's still an idea worth considering.

It would be for availability of water rather than pressure boost, although some boost as you said will occur....Normally you wouldn't need a tank on a building less than 6 stories, but there seems to be a problem with water availability in the quantity needed...They have water tanks on one story buildings in Mexico...In this case the roof tank would feed the existing booster pump...Then again it could be a valve problem, as somebody said...but maybe just undersized or obstructed water lines feeding the building....

"As a bonus, a large roof tank will dampen building sway"

No, it will change the frequency of oscillation. This may be useful if the resonant freq of the building is a problem. But is not necessarily a good thing.

I agree a roof tank for the cold water

Is this well water ? Does it have a lot of minerials in the water like Lime from the rock ?

I'd suggest running the hot water line in a ring.

Hot water is continually circulated back to the boiler so there are no hot/cold spots in the pipe. That way the local shower temperature controllers will have steady conditions to work with.

It also means your guests don't have to run the "hot" water for 10 minutes before the water heats up.

Simple solutions are often over looked. Adjusting the hot water temperature to 105 Deg. F, and not mixing any cold for your bathing will result in a comfortable shower for most folks; it will save money, and prevent people from getting scalded.

1. With a 4 story building the available water pressure from a roof mounted water storage tank will be insufficient in the upper stories of the building.

2. The existing structure may not be structurally viable to support the additional load of stored water + tank Dead Load. Additionally, with a tank atop the building, the existing structural elements may not be robust enough to withstand the inertial forces induced by a seismic event.

3. Aren't rooftop water storage tanks primarily used for fire flow requirements in lieu of providing adequate domestic water flow and pressures throughout a tall building, like what we see in NYC?

Why not install hydro-pneumatic tanks on both the cold and hot water supply lines to equalize the water pressure differentials induced by the booster pumps? Just a thought....and I'm not a Mechanical Engineer by any stretch of the imagination.

Just adding my 2 Cents worth!

It looks like more than one issue; temperature and pressure.

Temperature should be regulated at the shower valve if the proper valve is installed. Setting all the hot water at 105 degrees F is not the answer as other areas of the hotel may need higher temperature requirements. The temperature at the lavatories is not mentioned.

Pressure: Could be several things; suction lift or continious pressure on the suction side of the pump. Most problems with pumps are on the suction side. Water softeners are not mentioned which can have a substancial pressure reduction. Is there a booster pump on both the hot water and cold water? Usually a pump or pumps should be on the cold water at the water supply to the building.

A return line circulator on the hot or tempered water is a great idea. as is insulated water piping.

It is difficult to make an imformed decision without full specifications and piping layout.

The water tower may work but would be costly and still would need a pump to raise the water to this greated height.

YAR

<...Setting all the hot water at 105 degrees F is not the answer ...>

Quite. Water needs to be stored at >=60degC/140degF to kill-off any bacteria within it. This setting is too hot for comfort when issuing from a shower head.

Let me speculate you only drink water that is 140 deg. F., or greater to avoid the bacteria that is found in cold water. Washing Dishes or laundry in a commercial setting, would require elevated water temperatures to disinfect (because of bacteria introduced to the these items). Water is chlorinated and tested to control the pathogens that could make you sick.

Don't forget, water heated with microwave energy is bad for you.

I've been avoiding this thread, mostly because the OP likely doesn't want to spend even a penny to solve his problem of poor design or build.

so, I think they are all safe from microwaved water. $$$$

Well? Were the inlet pipes inadvertently crossed over?

we have faced the same issue in a hospital water supply system. after several trials we found one damaged shower mixer. cold water passes to hot water pipes through the mixer .in such case it will affect the near rooms for the damaged mixer .