×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Combined Hydronic Piping

Combined Hydronic Piping

Combined Hydronic Piping

(OP)
Hi all,

Has anyone done a combined hydronic space heating and domestic hot water piping?  I have a boiler that will provide heating to my VAV boxes while running its hot water through a heat exchanger for domestic hot water.  I am having a hard time coming up with a schematic diagram that will show how this system is controlled, the number of pumps needed, the sizes of the pumps, where to put the control valves, etc....  Has anyone done something similar and is willing to share his/her knowledge?

Thanks.

RE: Combined Hydronic Piping

You could try the ASHRAE books, or if you just want nice, simple "cut to the chase" info, go to www.heatinghelp.com There's a message board mostly populated by contractors who do residential hot water & steam heating, and another section with inexpensive books.

RE: Combined Hydronic Piping

You will need two separate loops, one for the domestic hot water and one for the heating.  I have used a mixing valve on the heating loop to control the temperature of the heating water as the boiler water must always be the same hot temperature to create the domestic hot water.

RE: Combined Hydronic Piping

be sure to pay attention to pressures in the system if you decide on more than one circulation pump (one for the domestic water, one for the hydronic heating system, etc).  also make sure that your boiler is getting the right amount of water flow, at the correct temperature

i have been trying to find this information also, and have found it very difficult to find.  the boiler mfg's don't publish much info, and the heat exchanger mfg's don't go into enough detail to be of much help.

RE: Combined Hydronic Piping

This is a handy web site for engineers and it may help you find what your looking for:
http://wea-inc.com/mainfrm.htm

RE: Combined Hydronic Piping

Several companies that offer combination heating/hot water boilers have prepared layout for piping/control of such system. It is based on use of "hydraulic switch". Priority is given to hot water consumption and pressure loss, when opening hot water tap, triggers "switching over" to hot water heat exchanger. However minimal circulation in heating system must be maintained to avoid hydraulic hammers.

Try this:

http://www.diyfaq.org.uk/plumbing/combi.html#pressure


New Audel HVAC volumes (all three) give some very usefull data on switches and all components.

http://www.amazon.com/exec/obidos/search-handle-url/104-0733410-8763900?%5Fencoding=UTF8&dym=0&search-type=ss&index=stripbooks%3Arelevance-above&field-keywords=audel%20hvac%20library

sunshine

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources