Gallons of Glycol

[ben]

I have a model and I'm trying to figure out the total gallons in my heating and chilled system. I have the heating supply, heating return, chilled supply, and chilled return all set to 30% propylene glycol. Is there a way to figure out how many gallons of glycol and how many gallons of water will be in the heating system and in the chilled system? Even if it just figures total volume, we can do the calculations of how many gallons of glycol & how many gallons of water.

[HVAC-Novice]

Create a "Piping System" schedule. One of the parameters it can display is "volume". 

Obviously you need to have set up the piping systems properly (as required for pressure drop calcs etc.).

You need to add the volume data for all equipment data (coils, boilers). I don't recall if you need to add that separately or if the piping system will include those automatically.... you need to try that out. 

I use that to size expansion tanks and see the value for expensive glycol price calcs. 

You could create a parameter with % and multiply that with the volume to get gallons of pure glycol. 

I would not trust a contractor to mix it on site and would specify pre-blend glycol anyway.

hope this helps.

[J.Wehmer]

Schedule>Piping Systems>Volume

Add other columns to refine your search/customization;

[ben]

Here's the problem I'm having.

All the different system names that the engineer drew in here. If I uncheck itemize then I get this

[ben]

@HVAC-Novice 

I did the pipe system schedule and have a volume parameter, but in some systems the engineer has hundreds of different system names (not sure why so many); I used his model and detailed it for coordination and prefab instead of starting from scratch, so I was also using his already established piping systems. The only thing I changed was in the piping system, I changed it from Water to Propylene Glycol - 30.

I didn't add any additional calculations for the equipment, just made proper piping connections to the equipment in the model. I'm not sure if it adds the equipment into the volume calculations or not. Some of the mechanical equipment isn't in my model, since it's being supplied by the HVAC contractor (we're just doing plumbing and hydronic heating & cooling/chilled); things such as the pumps, boilers, cooling towers, etc are in my model, but things like the chillers, AHU's, VAV's, etc are in the linked model from the tinners. I'm not sure if it calculates equipment from linked models either.

The best I have been able to come up with so far is sort by abbreviation, uncheck itemize, and format volume to calculate totals which gives me this

I'm not sure why so many of them are at 0 gals or very few gallons. I tried doing a calculated parameter taking volume * .30 but all it calculated was one of the two "other" systems.

We are the contractors and after cleaning and flushing the system, we are mixing on site with DI water, pure glycol, and inhibitor, it's not our first rodeo. The original BOD didn't even spec glycol or inhibitor, just city water; we recommended the glycol, inhibitor, and DI water. That's why I'm trying to figure out the volume, so we have an idea of how much needs to be ordered (I'd be trying to figure out the same thing even if pre-blended was spec'd). Once everything has been circulating for at least 24 hours we do a field sample, and if it doesn't appear to have a high enough glycol percentage, then we calculate how much more pure needs to be added, and we add it; or if it looks like we are at the correct percentage than we send a sample to the glycol supplier and they do a more accurate lab test to see check the percentage, they tell us if we are good or need to add more, and then they send us a comprehensive report.

[HVAC-Novice]

This is just speculation: the designer may not have set up the systems properly if he/she didn't use Revit to calculate pressure drop. the systems also can split apart, and Revit is susceptible to needing some manual adjustment. Especially when you have parallel pumps, or mix systems (i.e. primary/secondary loops). I also assume some equipment being in the linked model and not in yours may play a role. i never worked in a model where not all mechanical equipment originated from my model. 

With that said, it may not be possible to get a reliable number from your model. At least not without a lot of effort. 

I'm curious why the system was designed without glycol (assuming no need for freeze protection) and now glycol is added. I understand adding the inhibitors. but we usually only add glycol because of freezing. Did the designer forget about freezing? 

[ben]

I was hoping to at least get a volume calculation from the piping (less the equipment in the linked HVAC model). We could at least find the volume for the chillers and AHU from the tinner's shop drawings, add that into the piping volume, and add some extra for the VAV coils.

There is very much a need for glycol here; we are definitely in a freezing climate. However, the GC is from somewhere down south where it doesn't freeze, and didn't understand the concept of freezing beyond their kitchen refrigerator/freezer. We tried explaining it to them multiple time, but they didn't seem to understand why we thought it was important to put glycol in the system until we told them we wouldn't be filling the system unless they signed a waiver.

In the fall of last year, when the temp was on the decline and only down to about 40 degrees, one of our welders told me that one of the GC's employees said to him, "I don't know how you guys live in this cold weather." Our welder replied to him saying, "Cold? This is just chilly. Stick around until January & February and you'll see what cold is. -20 is cold." He said the guy's eyes got as big as saucers when he heard "-20"