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How well do cooling only VAV's with perimeter heat work?

How well do cooling only VAV's with perimeter heat work?

How well do cooling only VAV's with perimeter heat work?

I'm in climate zone 5b and we have an existing building that we're going to do a TI for that has cooling only VAVs and hydronic perimeter radiators. I guess I'm wondering how hard we should push the owners to upgrade to VAV's with heating coils. We never put in cooling only VAVs nowadays and I don't know any other engineering firm that does; they all have reheat coils with new construction now.

Does anyone have experience using these or has had issues with these? My main worry is that some of the center offices would get too cold due to the VAV's supplying 55-60 degree air for the minimum ventilation rate. Seems like there would be a lot of issues with interior zones getting too cold with no way to heat them.

Thanks for your thoughts.

RE: How well do cooling only VAV's with perimeter heat work?

My experience is that the interior office type spaces you can usually get away with it since the minimums are so low. But the conference room high occupancy high minimum airflow spaces are the issue. You can resolve those by using minimum ventilation reset strategies which is somewhat code required anyway.

A simple exercise to communicate your issue is to see what your minimum airflow is to some example spaces and balance it against some light and a lower than normal amount of people and see what the space temp would balance out to be. Communicate this to client and see if they can live with it - and they probably have been since it’s the existing condition. I’d they can’t live with it then you have to dig into how complicated it is to connect reheat coils to the hot water already there. Is or can it be year round, what temps are available for reheat, how is it controlled and will that work for the reheat coil when you need it.

RE: How well do cooling only VAV's with perimeter heat work?

Thank you very much for the comment, it's very helpful. This is a new company moving into the building so they haven't been living with it and it's a pretty fancy remodel with lots of conference rooms. I'll do that exercise and bring it up for their decision. Thanks!

RE: How well do cooling only VAV's with perimeter heat work?

For smaller core zones, set it to a very low minimum. We have done VAV only without heat (cost saving) without significant issues. Just communicate to the owner the limitations of the system as the other poster indicated.

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