Cold walls , cold people

hvacfreak

After recieving the beating in the meeting and running some service calls today I picked up my drawings of this project ( lucky me I get to be in charge of the coil repipe ). I did get a chance to look at the drawings today and am now able to see how WRONG the system design is. Here's what I see on the drawings...

1) Small fan-coils piped with 1/2 inch nominal copper with 140 degree supply water temp ( running 155 on Friday ..hmmmm ). These units are serving poorly insulated outside walls ( old brick ) with leaky windows.

2) An expansion tank rated at 2 gallon capacity ( water bladder type ) speced...I think the one on site is larger than this ...I just started the take -off tonight. The lift ( fill pressure ) may not be correct due to a grade difference between two building sections ( need to review the site drawings ).

So , the way I see it I need to

a) Go along with piping the coils to the letter.
b) Size the expansion tank
c) Pick and choose a couple of walls and do some sort of load calculation on them ( even if it's a hand manual j ).

I did feel bad when I looked at the demo pages...they had 4 pipe ventilators ( floor mount ). They were better off before the renovation project. - freak

EDIT - There are actually a handfull of units piped correctly on site. I spoke with the owner and offered to do some performance testing on those just to see where we were at...he declined. I really think those served the areas we observed last week anyhow , lol.

hvacfreak

beat down

I had to walk through a project today with the design engineer , most of the occupants were not comfortable. It's an older structure with small fan - coils supplied with 155 degree water. The supply air temperature was approx. 78 deg. in most areas with most sensors ( located on interior walls ) at or near setpoint ...72 deg.( infrared thermometer ). The ouside wall surface told a different story as most read 64-65 deg ( avoiding windows that leak moderate to heavy ).

We ( company I work for ) have many of these small 4 row coils piped backwards from the submittal data ( supply and return connections reversed from the manufacturers intent ). The manufacturer is stating that the loss is from 3 to 8 percent efficiency ( minimal in the big picture ).

So we are being told that correcting the piping on these small coils is going to make things better. When I say small I mean most of our luch boxes are larger than these things. Hydro air , old structure , cold people...I'd say that they'd be money ahead to ask us for a credit to install some baseboard or something. Also fighting a very small expansion tank that they won't admit to being undersized ( I'll be doing a take-off on my own time on this one ). The next thing I'll do is break into a finished wall to determine coefficients for a load calc too , lol.

Everyone here knows 78 degree air won't work in the structure I described ( or even 80 degree for the piping dispute ) ...what FACTS am I missing ? I need to explain to the owner that the engineering firm let them down ( without baseboard or radiant heat on those old walls ). Ammo please. - M

[Deleted User]

go to...

www.healthyheating.com and get educated on human comfort and MRT.

It's a start.

ME

EBEBRATT-Ed

Your on the right track. BASEBOARD is the only thing that will fix this (IMHO). Seen many jobs like this. "Warm Air" will not work on these jobs.

ED

hvacfreak

Thanks

I appreciate all input on this... alot of fintube could be bought for just our in - house costs on this. -m

Boilerpro_5

A much better solution than baseboard....

would be radiant wall panels. Baseboard is still hot air, but spread evenly over the cold walls to help warm them. The radiant panels will radiant warmth to the occupants and counteract the chilling effect of the walls and probably be much more efficient too, since the walls can still stay cool, but the occupants will be warm.

Boilerpro

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Brent_2

I don't know where the 155° originated from but I would suggest to gain the 8% capacity loss bump the water temp up 5° (or whatever the calculations come up with) and see what difference that makes. Even if for whatever reason they don't want to keep the water temp a little higher it would be a good test.
Unless the zones are open 100% and you are not meeting setpoint adding 8% capacity will do nothing.
You could also change the piping on 1 or 2 units to show that it has nothing to do with the issue.

Tombig_2

Just an observance

It seems most circulated warm air systems need a "bump" when it gets really cold outside. I.E. when the temps drop into the single digits some radiation is needed to eliminate the cold walls. Most scorched air patrons respond by turning the stat a couple degrees. In fixed temp systems supplied by warm air via HX or fan coil indoor setpoints just don't cut it. Radiation/convective systems don't require the same "bump"...Hmmmm!

Keith_8

water temp

hvacreak,
What is the fasination with the low water temps? It seems obvious that to improve comfort raising the water temp would be the 2nd step. The 1st step would be to have them tighten up the envelope.

If no one sees the wisdom of testing the units that are currently installed correctly what's the point of continuing? The outcome will be disapointing and someone is out more $ without the results desired.

It's a lose lose situation. The only thing acomplished is activity with no purpose.

Does your boss have the ability to admit making a mistake?

Tough spot your in,

Keith

hvacfreak

I know what you mean...we're just the mechanical contractor , we didn't design this. More bad news , I checked the size of the expansion tank ( under many varriables ) and it is plenty big enough. The heat loss versus design is easy ...it isn't explaining the hydronic issues. Too many things at once. -m

Tom Hopkins

comfort

Freak you said all were at or near setpoint.You dont have a temp problem you have a comfort problem like Mark said.Dan whats the one about the frozen food isle?

hvacfreak

for sure

I was thinking about choosing one wall and " reverse " engineering it with the numbers to arrive at the actual insulation value. But I understand what you mean..." sensible " temperature readings alone don't show the big picture. -M