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Hydronic Cooling effectiveness/cost?


Hi. I hope this question isn't too random, but I was recommended to reach out here by a colleague of mine whose husbands posts here haha.

My current situation is that I'm looking to move into an apartment, however this is a 37-story building that used to be an office turned into a residential property. As you can guess by now, the units are heated/cooled through a hydronic system. In case it gives more context, it was built in 1986.

My main concern comes from the fact that when I toured the unit, I turned on the AC to 70* to cool down the place for ~20 minutes, and realized afterwards it wasn't as cool as I had expected. The questions I have are:

  1. Is it expected for a cooling setup like this to take much longer to cool down an area, if at all? Or might this be more related to say the height of the building (25th floor), the temperature that day (~80+), etc.?
  2. If it does take longer or is less effective, would this potentially be a reason for my electricity bill being higher than a more typical setup in an apartment (ducted?)

Here is the realtor's explanation of the setup verbatim:

"the AC is a hydronic system which heats/cools with water from the bldg and it goes through coils then a fan blows the air from the AC unit in the ceiling. It takes a little longer than a typical AC unit. I can ask the building engineer to stop by and check if it’s blowing cool air. He has a temperature reader device to check the temperature of the air coming out of the vent."

I'm sure these are quite silly questions, but thank you in advance anyways!


  • hot_rod
    hot_rod Member Posts: 22,483

    What was the temperature inside when you turned it to 70? How much did it drop in 20 minutes? Were the registers blowing cool air.

    I wouldn't expect much change in 20 minutes

    The response will depend on many variables, one being the load on the space. South facing glass? The solar gain can be a big load.

    Do you really want a 70° space temperature?

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • DCContrarian
    DCContrarian Member Posts: 305

    Hydronic systems are very common in commercial buildings and they work well. Usually utilities are included in the rent because there isn't any way to meter usage. They aren't common in residential because there is a very limited selection of air handlers for sale in the US that are small enough for typical residential loads.

    What are also common in big buildings are water-source heat pumps, which are like the units found in single-family homes but instead of each unit having an outside unit, water is used to carry heat away and there is a cooling tower on the roof that removes heat from all of the units. In this setup the heat pump is in the apartment or office, and each tenant can be responsible for their own utility bills. If you have separately billed utilities this is probably what you have.

    In either case, the technology is capable of delivering plenty of cooling. You don't say where you are, but 80+ isn't that hot, in most of North America the heating system would be designed for 90+ temperatures. With a hydronic system I could see it taking a couple of minutes to turn on, but after that it shouldn't have any problem cooling things off.

    I would take them up on their offer to have someone look at it. If their final answer is "it is what it is" you need to think long and hard. There are lots of buildings that ust have poorly designed or installed heating and cooling systems.

  • ke1
    ke1 Member Posts: 2

    Unfortunately I hadn't checked the temperature prior, but can confirm there was at least cool air blowing. The unit faces north, but maybe a few factors played a part e.g. middle of the day, large windows, etc. In any case, I appreciate the reply!

    In this instance, all utilities are covered. Electricity is covered up to $100 and then the rest is out of pocket. So it sounds like it might be an actual hydronic system?

    The unit is located in Downtown Los Angeles so I agree that it was almost assuredly build for 90+ temps. I suppose it's best to wait on their reading tomorrow and maybe even one last visit to the unit to be sure. Thank you very much for your reply as well!

    EBEBRATT-Ed Member Posts: 15,840
    edited July 3

    Could be as simple as a dirty air filter. Have building maintenance show you how to change filters if they do not do that as part of their maintenance (they should). Filters should be preplaced at the bare minimum 2x/year and likely much more often.

    Also, ask maintenance if the air handler is hooked up as a 2 pipe or 4 pipe system. 4 pipe is good, 2 pipe is not so good.

  • JakeCK
    JakeCK Member Posts: 1,417
    edited July 7

    Whenever someone asks if one really wants it at 70f...

    Why yes, some of us really do want it at 70, or lower.

  • jumper
    jumper Member Posts: 2,333

    Many think that higher water temperature saves money. That makes cooling slower. System in my experience work way better when chiller set for 38 ° than when it is set for 45°. Especially when air handler's coil has few rows. Big air handlers, say 60,000 cfm, will have seven or more rows.