Help with Condensation in Fitness Room

[S_Line]

Just my luck,

A Function / fitness room for a local council.

They wanted heating and cooling, so we installed a Mitsi Heavy Underceiling unit, with 7 K.W of Cooling / heating

The room isn't that big, about 10mts x 10mtrs x 2.4 ceiling.


It has opening windows.
Same old story, its on the cheap.
No probs with the AC unit, heats the room up in no time at all.

The problem is when they have a Fitness class in there.

The flooring is all new Vinyl type which was recommended to them.
The floor gets damp and they start slipping over

The outside ambient is about 8 degrees C and can be lower at teh moment,

They turn the AC unit on 18deg C cooling.

Now the room temp never gets above 16 degrees even with a fitness class going on,
So theres no drying effect going on, they have the windows open for the fresh air.

But everything condensates.

They have tried heating the room up before the class, and then cooling at the start of the class, but the unit soon brings the temp down to 18 degrees and cuts out.


This is the only Fitness room we have done with a Vynl floor, they are always a heavy duty Carpet.

I have sujested to have a 3 K.W heater on, to bring up the temp, so that the AC unit will start to cool.

They are going to try that next.

Has anyone had this problem ?
Please help

[Gary]

The outside ambient is about 8 degrees C and can be lower at teh moment,

At those temps the outdoor air will not add moisture and if anything should help to dry the room.

They have tried heating the room up before the class, and then cooling at the start of the class, but the unit soon brings the temp down to 18 degrees and cuts out.

You might try reversing that, cooling as much as possible, then heating. Or just simply open the windows and bring in lots of fresh air, then heat.

And when in cooling, the blower should be at its lowest speed in order to drop the coil temp and remove maximum moisture.

[multisync]

Does it not have a dry function you could try?

Multisync
london

[Brian_UK]

What type of building is it ?

What is the floor made of or is it insulated etc.

Why does the floor get wet? If you say condensation, is it over the windows and walls as well?

[Gary]

What is the floor made of or is it insulated etc.

Good point. If the floor is not insulated (concrete slab?) the surface may be cold enough to condense moisture, even in a relatively dry room. But then, why only during a fitness class?

[Abby Normal]

get the RH and work out the dewpoint. If the slab is cool then you need to power ventilate to get the room air dewpoint down lower than the floor slab temperature. There is a fair bit of humidity being generated and the air is not all that hot,

Mechanical dehumidifying will not work very good under those conditions.

Cheapest route, a fan to exhaust 5 to 10 l/s per person, open a window to let some air in. Better approach, heat recovery ventilation

[Thermatech]

What is the wet bulb temp of the room air?
What is the off coil supply air dry bulb temp ?
The floor temp must be below the dew point of the room air for condensation to form.
Did you measure the actual temperature of the floor surface ?

I wonder if you have very low off coil supply air temp & unit is dumping that very cold air onto the floor which is making the vinyl floor cold enough ?

Perhaps worth deflecting air out to the walls & let it drop down to floor first then it might pick up more heat before it gets to the floor.

Or is somthing else making the floor so cold ?

If you take some more dry & wetbulb temperature readings & smoke test the air flow arround the room you should be able to find out what is causing the condensation.

The outdoor unit is cooling in very cold outside ambient condition. Low ambient HP control fitted ?
Is the discharge pressure & suction pressure a bit low ? That would make lower than needed evaporating temp at the indoor coil & extra low off coil temp.
If you can adjust the discharge pressure up higher the evaporating temp at the indoor coil will be a bit higher & the unit will cool for longer.
It will still remove moisture but can only do so if the outdoor unit is running.
If the unit is stopped half the time because its at set temp then its not removing moisture during the off cycle.

[Abby Normal]

Good point. If the floor is not insulated (concrete slab?) the surface may be cold enough to condense moisture, even in a relatively dry room. But then, why only during a fitness class?

sweating to the oldies will elevate the RH and dewpoint, the bigger the sweatier

[Abby Normal]

they heat the place up themselves, the ventilation will cool them off and keep the RH down, two birds with one stone

[S_Line]

Thanks for all your replies, im really happy i have had so much feedback over this one.

I will try and answer your questions.

AS soon as the fitness training starts the floor and mirrors condensate.

The unit has a dry function, but cant dry below 18 degrees.

The room is about 15 degrees C, they like it at that temp.

The floor is solid concrete, its a modern extension to a old building so SHould have been built with insulation in the floor.

When i looked at the job, there was a carpet on the floor in the room
Now they have taken the carpet up and put down vynl.

SOunds like a ventilation task, Either a couple of large Vent axia wall mounted heat recovery units, or a large roof units fan on the flat roof.

Either way, i can see them complaining as they were expecting the AC unit to provide a God like task.

[Thermatech]

When the room is not being used 15 deg C DB & assume 50% RH.
WB will be about 10 deg C & dew point about 5 deg C.
Very unlikely that the off coil temp of the supply air is lower than 5 deg C.

When the room fills up with people on a fitness class assume 15 deg C DB & 90% RH. The WB will be about 14 deg C & dew point about 13 deg C.

Every possibility that the off coil supply air is lower than 13 deg C even with low ambient HP control.

In view of the type of indoor unit with one supply louver blowing supply air horizonally into the room then the air will as it runs out of velocity fall straight to the floor & could still be below 13 deg C as it hits the floor.

If you can fine tune the HP control to acheive higher evaporating temp at the coil the supply air could then be slightly higher & might solve the problem.
Make sure the unit is always at highest possible fan speed will also help keep evaporating temp up.

[Abby Normal]

Once you get to conditions around normal room temperature and 35% RH you come up against a brick wall as far as mechanical dehumidifying goes. The problem is the DX coils will want to freeze.

If it in fact gets a fair bit colder out during the winter, heat recovery ventilation will do the trick, and when it is still somewhat cool out (aka above freezing) you can do the free cooling aspect, stop the heat recovery and not temper up the fresh air.

Tell them it is the correct approach and the green approach to their problem.

[Peter_1]

While cooling, you have a downdraft of the air.
The Mitsu's aren't circulating that much air, mostly to avoid cold draft.
Some suggestions:
Flore is always the coldest place in any room without radiant heating.
Isolating under the vinyl.
Small heating under the floor to increase dewpoint.
Adding air circulation very close to the floor.
Hire once some mechanical dryers and see if this is of some benefit.
I think with the cold and very humid conditions we encounter now these days - an din the UK it isn't that better - around 35°F and raining a lot these days that there's indeed a lot of moisture entering the room when circulating outdoor air.

[Andy]

Just my luck,

A Function / fitness room for a local council.

They wanted heating and cooling, so we installed a Mitsi Heavy Underceiling unit, with 7 K.W of Cooling / heating

The room isn't that big, about 10mts x 10mtrs x 2.4 ceiling.


It has opening windows.
Same old story, its on the cheap.
No probs with the AC unit, heats the room up in no time at all.

The problem is when they have a Fitness class in there.

The flooring is all new Vinyl type which was recommended to them.
The floor gets damp and they start slipping over

The outside ambient is about 8 degrees C and can be lower at teh moment,

They turn the AC unit on 18deg C cooling.

Now the room temp never gets above 16 degrees even with a fitness class going on,
So theres no drying effect going on, they have the windows open for the fresh air.

But everything condensates.

They have tried heating the room up before the class, and then cooling at the start of the class, but the unit soon brings the temp down to 18 degrees and cuts out.


This is the only Fitness room we have done with a Vynl floor, they are always a heavy duty Carpet.

I have sujested to have a 3 K.W heater on, to bring up the temp, so that the AC unit will start to cool.

They are going to try that next.

Has anyone had this problem ?
Please help

Hi S_Line

what about heat recovery ventilation to reduce the load on the A/C and to temper the air.

Kind Regards Andy

[Abby Normal]

While cooling, you have a downdraft of the air.
The Mitsu's aren't circulating that much air, mostly to avoid cold draft.
Some suggestions:
Flore is always the coldest place in any room without radiant heating.
Isolating under the vinyl.
Small heating under the floor to increase dewpoint.
Adding air circulation very close to the floor.
Hire once some mechanical dryers and see if this is of some benefit.
I think with the cold and very humid conditions we encounter now these days - an din the UK it isn't that better - around 35°F and raining a lot these days that there's indeed a lot of moisture entering the room when circulating outdoor air.

35F fog in London, has a dewpoint of 35F, so hopefully the floor is warmer than that.

You intorduce 35F fog into a room at 60.8F (16C) and it is like saying it has 38% RH.

That 35F fog has a lower enthalpy and moisture content than a typical air conditioning unit will supply.

So it sounds like the occupants of this fitness room heat and humidify the space, so bringing in cool outside air will bring the dewpoint down and stop the condensation.

If the outside air is colder than the floor surface, it will dry the space out if it is raining or not. If anything the system works in heating mode if the outside air cools the room off more than the occupants heat it up, to cut down on the heating that is when you use the heat recovery ventilation.

[Gary]

Winter is easy. Just bring in cold outdoor air and heat it to 15C. It will be relatively dry.

Summer is a little trickier. They will need an A/C that is capable of bringing the room temp down to 15C, with an evap air off temp of about 4C.

On the other hand, once they get the humidity down they may find that 15C is a little too cold. They may want something like 18C, where the dry mode works.

[Thermatech]

After the contractor has suggested a heat pump system & enduser has agreed, its difficult for the contractor to then suggest that was not the best solution after all.

Contractor needs to get full payment for the heat pump installation first then suggest what further improvements can be made at extra cost.

1/ Fine tune the low ambient control to get higher evaporation temp at indoor coil & fine tune air flow distribution in the room.
2/ Prove to customer condensation problem is resolved & not a reason for non payment.
3/ Following full payment, suggest benifits of heat recovery ventilation.

[Gary]

Make sure the unit is always at highest possible fan speed will also help keep evaporating temp up.

To dehumidify, we want the evap temp (and fan speed) down.

[Thermatech]

Customer has just spent a lot of dosh on fancy floor material which is glue bonded to the floor slab.
I dont think they are likely to agree to rip it up again to resolve this problem.

[Thermatech]

Gary

with all due respect to you,

the system could be overcondensing & the indoor unit running in coil frost prevention conditions.
The off coil temp could be 6 or 7 deg C.
The underceiling unit is blowing out into the room through one louver & blowing the air horizontally across the room.
The off coil air drops after about 3 to 4 meters & hits the floor still below dew point & makes the vynil floor material colder than dew point.

Making the fan speed slower will for sure make even worse.

Stop the cold supply air hitting the floor at below dew point temp = no condensation.
To achive raise evaporating temp with low ambient HP control & redirect air flow so that it does not dump cold air straight down on the floor.

Untill the contractor takes some wet bulb temps we dont know for sure but the possibility is that the humidity is not the issue.
The issue is the cold floor surface temperature.
So whats making the floor temp so cold ?

If the contractor can do some basic fine tuning & resolve this issue with only one more site visit then he will get paid. This is the contractors primary objective.
After that he can suggest alternative upgrade improvements.

[Gary]

The supply air cannot be below dewpoint.

[Gary]

the system could be overcondensing & the indoor unit running in coil frost prevention conditions.
The off coil temp could be 6 or 7 deg C.

That would be a very good thing. But in fact the A/C unit is not running at all.

And the mirrors are condensing, too. Apparently the walls are not insulated, either.

[Thermatech]

The floor material must be below dew point of room air for the condensation to form on it

agreed ?

So what is making the floor material so cold ?

If the a/c unit is blowing very cold air & dumping it onto the floor material & that is resulting in the floor material being below due point of the room air then ,,,,, that could potentially be the cause of the condensation.

Lets see what the engineer finds after he has returned to site & taken some more temperature readings.

Some inteligent readings of dry & wetbulb air temperatures , floor surface temp together with refrigerant suction & discharge pressure / temperature readings would show what needs to be done to resove this one.

[coolments]

Hi

I have come across this problem alot as the company i work for up untill recently had a national contract with a national fitness group for 4 years, problem is you get is maybe 20 people or more in these rooms for 1 hour or so doing special lessons like a spin class flogging them selves to death and sweating doing some form of intense work out.
The over kill on kit to combat this surge in humidity is just not cost effective, have you actually been in the problem room sessions to watch the condensate build up, i did with their site tech and most of the condensate bulit up by people not only sweating like crazy but squirting there faces and body with water bottles to cool down increasing the effect.
Instead of going over board on vent and more kit we used floor mounted studio fans to create high air movement around the room and floor during intense sessions, this heped with evapourative cooling on the skin so they didnt over heat as much and feel the need to squirt water and the high air movement also helped keep the condensate from building up.
Think about it, it doesnt matter what temp the room is if you are training intensley and there is low air flow over you, you will over heat and will sweat more, air flow from a single split is just not adequate even if it controls room temp, the fans certanly improved the situation for my client, may be ok for yours too.

[Gary]

The floor material must be below dew point of room air for the condensation to form on it

agreed ?

Agreed.

The floor is being cooled by the earth below the uninsulated concrete slab.

If we can't warm the floor, then we need to lower the dewpoint of the air below the surface temp of the floor.

The dewpoint of the outdoor air is something less than the temp of the outdoor air, which is currently less than the temp of the floor. Bring it in (while exhausting a similar amount) and warm it up to 15C.

[Gary]

Customer has just spent a lot of dosh on fancy floor material which is glue bonded to the floor slab.
I dont think they are likely to agree to rip it up again to resolve this problem.

That moisture on the floor is going to make the decision for them. Moisture weakens the glue. The vinyl tile is going to start popping up all over the place.

[Gary]

I think with the cold and very humid conditions we encounter now these days - an din the UK it isn't that better - around 35°F and raining a lot these days that there's indeed a lot of moisture entering the room when circulating outdoor air.

Bringing in outdoor air at 35F@100%RH (even if its raining out) and heating it to room temp, will in fact dry out the room.

[Thermatech]

Coolments

The floor mounted fans is a great idea.

As this is a health & safety issue the enduser could be sued if someone falls on the slippy floor & then the contractor could be looking at a public liability claim.

So a practicle suggestion which can be implemented imediately is just what the contractor needs.

[S_Line]

Goodness me loads of replies.

I think that a visit while a class is in use to take some readings may well be the best way forward at the moment.
I may even leave my USB dongle monitoring device there for a week to monitor temps and humidity.

[S_Line]

I emailed the customer today and reccommended to try two Pedastall fans standing in front of the two opening windows.
THese will bring in Fresh air and get some air movement in the room.

[Gary]

I emailed the customer today and reccommended to try two Pedastall fans standing in front of the two opening windows.
THese will bring in Fresh air and get some air movement in the room.

Best would be one pulling air in and the other pushing air out. Even better if the two windows are at opposite ends of the room.

[coolments]

Coolments

The floor mounted fans is a great idea.

As this is a health & safety issue the enduser could be sued if someone falls on the slippy floor & then the contractor could be looking at a public liability claim.

So a practicle suggestion which can be implemented imediately is just what the contractor needs.

You could fall and slip on any thing, the fans would be in a protected casing so pose as much risk as any other obstacle in the room so i think your comment is unjust. your not realy going to site them in the middle of the floor or in a through way. Also i think a few are missing the point, the original post states room floor only condensates during classes not all the time which will be caused by the people and there activities in there, if was a building fabric problem then condensate would be present all the time during cold weather would it not.

[Brian_UK]

You could fall and slip on any thing, the fans would be in a protected casing so pose as much risk as any other obstacle in the room so i think your comment is unjust. your not really going to site them in the middle of the floor or in a through way. Also i think a few are missing the point, the original post states room floor only condensates during classes not all the time which will be caused by the people and there activities in there, if was a building fabric problem then condensate would be present all the time during cold weather would it not.

I think that you have misinterpreted the post completely. The safety issue is the wet floor, not the fans

[coolments]

I think that you have misinterpreted the post completely. The safety issue is the wet floor, not the fans

Yeah true, maybe i was a bit hasty there, bad day in the office and all that...!! sorry thermatec, managers Prerogative to rant first, then think about about it and backtrack.

More relaxed at home with a beer now

Sline, what better excuse do you need to sit in a room and watch 20 women get sweaty for an hour with your dongle out.

[Brian_UK]

Yeah true, maybe i was a bit hasty there, bad day in the office and all that...!! sorry thermatec, managers Prerogative to rant first, then think about about it and backtrack.

More relaxed at home with a beer now

Sline, what better excuse do you need to sit in a room and watch 20 women get sweaty for an hour with your dongle out.

No, sorry, they should take in all that is told to them and digest the information properly.

Then they can spout off unrelated rubbish to their hearts content.

[Ke-Fibertec UK]

It sound like the air movement in the room needs to be increased, when we fit ducting in these high intesity ares, we direct air towards the walls to prevent condenstation forming.

[S_Line]

Well to report back, Its all gone quiet, as they have a leaking roof now, and need the outside unit un installed to re roof !

[back2space]

I think you need to change the direction of air flow. Can you direct the air flow up at the ceiling so that it is not falling straight to the floor.

I also think you need to increase are flow in the room so ceiling fans or floor fans could be a solution then you wouldnt need to have the setpoint so low.