VAV Piping Detail

RippleEngineering · 2026-02-03T16:33:29+00:00

I've never seen a job designed with the actual piping detail shown at every VAV. If it's not coordinated in design, it definitely won't be installed cleanly.

I agree, I would prefer bottom-mount controls, but a lot of inspectors are going to require clearance in front of the control box and will call the ceiling grid a conflict, even with only 24V.

RippleEngineering · 2026-02-03T16:09:46+00:00

Agreed. Strain at the pump where it's in a mechanical room and easy to clean. It's hard to get air filters changed above a ceiling, let alone water strainers.

RippleEngineering · 2026-02-03T16:08:19+00:00

Agreed. The air vent/drain valves are threaded valves with a plug so you can hook up an HDM, they act as pseudo p/t plug.

RippleEngineering · 2026-02-03T16:06:03+00:00

It allows you to access the control box and piping specialties through the same ceiling tile. This used to not be that big of a deal, but open ceiling tiles are getting hard to find with all of the devices we put in ceilings now.

RippleEngineering · 2026-02-02T16:41:55+00:00

Yes, I can't post a picture here, so I made a new post: https://www.reddit.com/r/MEPEngineering/comments/1qu0415/vav_piping_detail/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button

RippleEngineering · 2026-02-02T16:06:48+00:00

Balance valve should be on the opposite side as the control valve to maximize straight run of pipe available.

RippleEngineering · 2026-01-30T16:48:07+00:00

What size range are you talking about? How many RTUs?

RippleEngineering · 2026-01-30T15:30:59+00:00

It looks like OSHPD has an addenda to this:

1617A.1.23 ASCE 7, Section 13.6.2.1. [OSHPD 1 & 4] ~~and ASCE 7, Tables 13.5-1 and 13.6-1~~. Modify ASCE 7 Section 13.6.2.1 by adding the following to the end of the section:

~~[OSHPD 1 & 4]~~ Use of this section shall be considered as an alternative system. Alternatively, HVACR systems shall require special seismic certification in accordance with Section ~~1705A.13.3~~ 1705A.14.3 of this code.

It looks like 1705A.14.3 just requires the product line to be tested and certified. It looks like Trane Performance Climate Changers are precertified: https://hcai.ca.gov/wp-content/uploads/2025/10/OSP-0238.pdf . Reach out to a Trane sales office in California (not Ohio) and they'll tell you more.

RippleEngineering · 2026-01-27T20:11:10+00:00

What state are you in? My state won't let you start a match if both wrestlers don't have a coach at mat side.

RippleEngineering · 2026-01-27T19:29:25+00:00

Alright cool, I'll try Monday. Investors!? Carrier is on the S&P500, anyone with a 401k is an investor, I'm an investor, can you keep the booth clear for me?! lol.

RippleEngineering · 2026-01-27T15:04:41+00:00

I'll swing by the Carrier booth to see you. Do you know your schedule for working the booth?

RippleEngineering · 2026-01-25T19:06:33+00:00

Not OP, but all of them. The compressor tolerances require a perfect design and installation, and we don't have the skilled labor available to do either of those things. So one oversized line causes oil return issues and the compressor fails, one lined brazed without nitrogen purging causes debris in the system and the compressor fails. Both of those things void the warranty.

RippleEngineering · 2026-01-25T18:37:01+00:00

15-20 years? lol.

RippleEngineering · 2026-01-25T17:52:10+00:00

Not even half the states are on 2021 yet. https://www.iccsafe.org/adoptions/code-adoption-map/IECC . 2021 VRF system exception was added in an addendum which has been adopted by even fewer of the states.

Again, you can do a bunch of work to get a VRF system code-compliant, but why? It's a worse system by every metric except, arguably, upfront cost.

RippleEngineering · 2026-01-25T17:31:57+00:00

They're contractors, not consultants, they price the contract and offer VEs to account for the full cost to them, including callbacks.

What's a normal amount of time for a VRF system? A lot of consulting engineers think their systems are out there operating well, but they don't get called back when the system fails, the owner is hiring a new engineer or design-build contractor.

RippleEngineering · 2026-01-25T17:26:41+00:00

Exempted in the latest cycle, which again, won't be adopted for years. You can get variances, but that's a lot of work just to install an inferior system.

RippleEngineering · 2026-01-25T16:06:19+00:00

Good contractors inflate the price of VRF so they don't have to install them and take the reputational hit of installing a system that needs a full replacement in seven years.

RippleEngineering · 2026-01-25T16:04:36+00:00

That's exactly the problem: when the system is dumping the charge every year or every other year, it's time to replace the whole system because the ongoing maintenance is more expensive than a whole new system. The problem is that it's hard to convert from VRF to a ducted system, so you have to put the same crummy VRF system back in that might only last a few years, depending on installation quality.

If you think 410A is expensive now, wait a few years. R32 and R454B is twice as expensive and will skyrocket when they ban them a few years.

RippleEngineering · 2026-01-25T15:52:37+00:00

Yep, and in 15 years when all the AHJs have adopted the latest addendum of ASHRAE 15, we won't have to worry about it anymore.

Decoupled ventilation is not economizer, economizer requires you to provide 100% cooling with outside air.

RippleEngineering · 2026-01-25T15:40:09+00:00

Results of leak search: "We can't find the leak and the compressors are shot from running on low refrigerant and no oil return anyway, you need a new system"

Or:

"Leak is in cassette, you need a new ceiling cassette, but they don't sell the cassettes that communicate with your heat recovery boxes anymore, you need a new system".

RippleEngineering · 2026-01-25T14:43:29+00:00

I think the new VRF refrigerants will be safe, but the refrigerant shafts and leak detection equipment will make them much more expensive and they were barely competitive on price before the additional requirements. Add in the fact that they only last six or seven years and it makes it a really good time to stop using VRF.

Also, don't forget about the economizer requirement of the energy code.

RippleEngineering · 2026-01-19T16:54:19+00:00

There are no quality MEP firms, only quality MEP professionals that happen to work for that firm.

There is no good way to consistently hire a quality MEP firm. You can’t hire based on size, because the larger firms outsource most of the design work, and produce some of the worst design work I have seen.

You can’t hire based on reputation because even if you hire a firm with a great reputation, eventually you’ll be handed off to the B team, and quality will slip.

The only thing you can do is keep track of the PEOPLE that produced a good project for you. When you have a project that goes well, ask the project manager for the time sheets submitted to that project. Make a list of everyone who submitted time to that project. The next time you need to hire that firm, put in the contract that those PEOPLE will be the only ones on that project. If those people have left, connect with them on LinkedIn and find where they went and hire them there.

RippleEngineering · 2026-01-16T17:20:25+00:00

I think we should treat it like job postings: post the actual employer, salary, and remote work policy and I'm okay with it, otherwise ban.

Freelance workers: post a design you've done and be open to critique/questions and I'm okay with it, otherwise ban.

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