Bathhouse HVAC

[AxisCat]

I have been asked to provide a proposal to condition a bathhouse for a commercial customer. They would like for it to be air conditioned as well as heated and I am not sure this is even a reasonable request.

It is a small building approximately 600 square feet total containing (6) bathrooms, each with a water closet and a shower. And at one end is a small laundry room containing (5) residential style clothes dryers.

Have any of you done similar projects? What are your thoughts?

 

[RandomUserName]

Certainly seems doable. If they are budget conscious I would expect they will be OK with HV part of HVAC. I feel like the AC part is gonna kill em. Gut reaction. What region is this building located in the world?


EDIT: Note that in my state if you are doing any new or replacement MEP work in a Clas 1 structure (i.e. a structure that could be occupied by the public or employees) you must submit plans to the state for review. Dot your i's and cross your t's in regards to mechanical and energy codes for bathrooms and laundry rooms.

 

[AxisCat]

Thanks for the reply. This building will located near Kentucky Lake for use by campers. Finding registered engineers in my area is tough to do but I have one that may be willing to provide some guidance.

That was my reaction as well, it could be done but do the owners want to pay for it. If you were to approach this what would your first thoughts be as far as a cooling strategy?

 

[berkshire]

This looks like one of those jobs where occupancy is for only part of the day, possibly early in the day then later in the evening.
Can you use motion sensors in your plan for part time utility?
B.E.

You are judged not by what you know, but by what you can do.

 

[AxisCat]

So far i haven't had any luck finding an engineer and in all my years contracting don't remember any similar projects coming across my desk. My initial thoughts were a single exhaust/makeup air system but am now leaning toward a small multi-zone ductless and individual exhaust fans for each bath. This would solve my recirculated air problem and be much more efficient during light occupancy times. As berkshire suggested occupancy sensors or similar control could be employed on each exhaust fan.

Makeup air still bothers me on this system as it would be pulled directly from the outdoors through a louver in each door/wall. I don't have a good feel for how these small air handlers are going to react with extremely humid entering air conditions. I also worry about conditioning a room with an opening to the outside to a state that the entire room condensates.

Please keep the suggestions coming. Even if I don't end up with this project I will have hopefully learned a few new things.

 

[berkshire]

Axis cat,
Looking at your last reply it would appear that the bathroom doors are facing the outside of the building. Makeup air still bothers me on this system as it would be pulled directly from the outdoors through a louver in each door/wall. I know this is often done in multiple bathrooms to cluster the plumbing onto a common drainpipe. However in your case what is good for one system works against the other. Is it possible to re-layout the bathrooms to open onto a common passage way, this way you can supply conditioned air to all of the bathrooms via one air handler.
B.E.

You are judged not by what you know, but by what you can do.

 

[berkshire]

You can also install an economizer into the system for days when the air temp and relative humidity are not too bad. With all bathroom extractor fans running , depending on your local code you are going to be extracting either 300cfm , or 600 cfm.
B.E.

You are judged not by what you know, but by what you can do.

 

[ReverseCycle]

It some parts of the world it might be deemed wasteful to exhaust air conditioned air. To get around this you could utilise air to air heat exchangers which can also reduce the load on your AC unit. This is however a rolls royce solution.

 

[HVACMech]

You don't have to hire a local engineer. There are lots of engineers that work in multiple states. Find a bigger firm, google MEP engineers or MEP consultants. As said before these should be stamped drawing submitted to an AHJ for review. Otherwise you are breaking the law

 

[AxisCat]

I really am trying to do this correctly on all levels. I have already spoke to our code review folks and they classify this building as "Special use - Smaller buildings" I am attaching a page from our State building code that addresses requirements for Design Professionals. Even though stamped drawings are not required I am actively seeking one for a quote to this project for me. The last thing I want to do is break any laws.

I appreciate your time and input.

Best regards.

 

[greenen]

Junior engineer here, so take my post with a grain of salt, I'm learning as I go along.

I had to do a design study for planning purposes for a similar building minus the laundry room. The big problem we dealt with was the humidity condensing after a shower. At a similar building that is being replaced, the condensation caused mold issues. The solution we used was to have individual exhaust fan for each room on a timer. When the person comes into the shower room, they would turn on the lights which turns on the exhaust fan. Fan could run ~10 min after they are done. You will lose heat, but it is the best of a tough situation. This way you are not exhausting heat from the other 5 stalls when only one is occupied. We proposed heating the space with a small boiler and radiant floor heat with radiators in each shower room.

Personally I do not understand why they would want cooling for the shower rooms. Why not take a cool shower if it is really hot out? You could run the exhaust fan all the time to get some additional airflow during the summer. Cool water from the shower may also cool down the space.

For the laundry room, you could add its own mini split system with separate ventilation system. That room makes more sense to be cooled. I would not want to do laundry in 90 degrees.

 

[urgross]

Sounds like some upscale camping. If the laundry and bathroom have to be air conditioned, why not go to a hotel?

 

[berkshire]

urgross,
I was just visiting a ( Camp site ) today , the motorhomes pulling in there cost more than my house. I am sure that if Axiscats camp site is on even half this scale, there will be more than enough money for this facility.
While I was there I checked the bath rooms and showers , Men's and women's back to back ,on a common sewer. 4 shower stalls then 4 toilets side by side on each side on a common row , a brick wall enclosing outer perimeter of each, with a single access door for each sex at either side of the outer wall. A vertical furnace/ with evaporator coil in closet, one for each side, one for the men's , one for the women's. Units were in heat mode this morning, However there were two condensers at the back of the unit ,one for each side.

You are judged not by what you know, but by what you can do.