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Yes the expansion tank is sized for the entire system, and as far as I can tell the system was designed this way. All the pumps are identical, from the flow rates and pump curve/design point the pumps were sized to provide system flow with 3 pumps online. What I meant by "Each chiller has...

I have inherited a chilled water system with a unique design that is having problems. The system has four 15 Ton chillers that are water cooled. Each chiller has its own pump; the original design is for 3 chillers and 3 pumps to be online at any one time. The unique aspect to me is that 3 of...

Thank you for all the responses, I did some more digging and the original flow was about 85 while the new flow will be about 113. The header pipe size is actually 2 inch which I am more happy with, still not ideal if we were doing this brand new. The problem we are trying to correct wasn't...

Thanks for the responses. The 3 way valves are on/off so the flow is either going through the coil and then to the return or straight back to the return. Both routes run through a constant flow fitting in the return line. I will have to look up the numbers to be sure, but the original flow...

I am working on a system that has a 1-1/2" common header from 3 individual pumps. We didn't do the original install but the 9 air handlers that were originally selected didn't perform so we re-did the heat load calculations for the new units and the chilled water to nearly all of the units has...

Thanks for the quick help littleinch and hpost.

First off the flow through each AHU is fixed but they are not all the same GPM. Each AHU has a certain GPM based on the room(s) it is cooling. I think the way you have described it is how I did the calculation. I started at the pump and took into account the total system flow in the...

So, let me show this in a quick diagram to make certain I got it right. In the attached picture, if the pump is supplying water to all the Air handlers (AHU's) (the system is fully open), then the pump head for this system would only need to be calculated for the losses from the worst case...

I have a quick general questions. For a chilled water system that is closed loop (the supply goes out from the pump through the supply branches which feed different cooling coils and then all feed back to the return branch and back to the pump) when I am calculating the pressure drop to get the...

<http://www.adoptionmultimedia.com/?attachment_id=729> I am designing a chilled water system that will use two 150 ton chillers and two pumps, this system will be a closed loop system. See the diagram for what the chillers and pump set up will look like. Only one pump and one chiller will be...

Thanks for the references, I will check them out.

I am working on a project that has Direct Expansion HVAC units installed to cool a birthing barge. The condenser units are on the roof and the AHU's are in the spaces throughout. We have been asked to go back a decide where refrigerant monitors should be located in the spaces below. Is there...

With time constraints we can't go out at this point and do a new control system with valves. I am going to try and do the control valve with the flow meter and PLC. Do you have a recommendation for this type of valve and controller? We have simple Ventui flow meters in the system already and...

I agree, but this is what we were told they wanted so its what we will give them.... Thanks for your help

The constant flow fittings we use work by a diaphragm that as pressure increases the diaphragm is compressed and closes off the flow area effectively regulating the flow as pressure changes. They have a 10% tolerance so they aren't incredibly accurate but they are mostly maintenance free.

LittleInch thanks for the response. The system is using on/off solenoid valves. So when the thermostat in a room wants heat it turns on the valve and the AHU will get max flow until the thermostat turns it off. Also, the chilled water is set up using constant flow valves for each AHU. So...

Hi all, I am in the process of designing a chilled water system and have gotten to the point of running calculations to figure out the pump head I need. The system is a closed loop chilled water system that has a demand of 480 GPM. There are two chillers and two pumps, with one chiller and...