hot water supply system

[dt174170]

Untitled

• dt174170
• 23 May 2013
• 1

There is the hot water supply system of a hotel, some customer have complain the temperature is not high enough and it is found that there is dead leg existing. I need some help to solve the problem. Thanks

1. Where can I find others hot water supply system is different with the above.
2. How to deal with the dead leg and maintain the temperature of hot water.
3. I want to know if any eddy would happen at point A (it is a point of assembly of return water) to slow down the flow rate of return water? If so, how to deal with it?

 

[Onetap]

Your diagram is too small to read but too big to study for free.

I'd guess floors 1 and 2 get hot water, 18 and 19 don't. You probably need balancing/regulating valves on the return branches, to reduce flow to the outlets nearest the circulating pumps and so increase the flow to outlets furthest from the pumps.

The flow rates should be very small, just enough to compensate for the heat lost from the pipes. The pipes are, inevitably, oversized for the flow rates. Similarly, the pipes have to be properly insulated. You need regulating valves on the return branches, sized to regulate the very low flow rates, to throttle down the excessive flow rates on the lower floors.

I have seen unregulated systems where the upper floors got no hot water and the return pipes on the lower floors (2"+ copper) were eroded at the bends due to the high flow rates.

Have a look at the Danfoss, MTCV valves, self-regulating thermostatic valves for hot water supply systems. They restrict the flow as the return water gets hot, making more flow available for where it is needed.

http://www.danfoss.com/United_Kingd...TCV/e340b0cb-566a-4e71-8a0b-9733a407123b.html

If there are dead-legs, or the water is only warm, there is a genuine risk of legionella. In the UK that could get you sued for huge amounts by irate guests; you might mention that if the management can't find money for improvements.

 

[neiltheplumber]

As above, probably needs balancing or the return pump could be on its way out. Also are the taps on tmv's and do they just need adjusting? Dead legs should have been highlighted on risk assessment which should be updated every two years and any recommendations of work should be carried out, ie "remove dead leg".