Wet heat in new 4 story/128 unit

j gryck

I have the opp. to take a building away from scorched airheads. Building has 4 floors, 128 units, natural gas. Units are all 1 and 2 bedroom, small. I haven't done this type of work in 20 years, looking fo help, options on design, ect. Not sure whats changed over the years. Owner may be open to radiant.(done alot of this lately in single families)

Mike Kraft

One thought

With that many dwellings you may consider using panel rads.You could pipe one or more manifolds per floor in a hallway that is accessible for service.From there you can run your feed and returns to each rad.Then install a TRV on each rad and use a constant circulation stradegy for control.Add a weather responsive control on the system and each tenant can control their comfort apt. to apt.Using PAP or pex you will have a great system and still enjoy the comfort of radiant.........just not under the toes:)

Joe_13

I agree. Radiant flooring would give you thousands of feet of places where leaks could occur over time. Too many renters/condo owners doing their own renovations that tubing could get damaged. Rad panels or good old BB with copper tubing sounds like the time tested proven technology to me.

[Deleted User]

Good old base board...

ain't the same as good old radiators. It IS cheap, I will give it that to it's credit.

The comfort level with radiators is completely different, the aesthetics are completely different,and the installed cost are different (higher), BUT, (and yes, that is a big but) it represents quality and value which warrant the additional expense. It has something of value that you can place a value on. This means that as condominiums, they can be sold as condoMAXIMUMS. Homes with radiant heat!! It means the difference between marketing an apartment house, versus apartment HOMES. Apartment homes with radiant heating!!

It can make a major difference in the makeup of the people living there and STAYING there because it is SO comfortable.

I agree with what the Cheesemeister said. Set it up for continuous circ with outdoor reset, with individual TRV's at each radiator. And, while you're at it, do the DHW for the building too. You've already go the horsepower there, might as well put it to use.

Install the PAB (pressure activated by-pass) valve at the furthest point of use and the main piping distribution system becomes a part of the radiant picture.

You could pipe the whole thing parallel direct return, saving some money, because the system will be self balancing.

It just seems that so many of my competitors are stuck on baseboard as being the only other means of hydronic heating other than radiant floors that I thought I should speak up.

Maybe I should keep this secret to myself...

Think outside of the tin box, Grasshopper...

There's a WHOLE nuther radiant world out there that's being overlooked.

Raising the bar for all mankind to follow,

ME

hot_rod

Where are these located?

Is cooling a concern? Hard to sell or rent anything these days without cooling. Except in the mountains! Typically a hydronic system would have a chiller option and use small airhandlers in each unit, often ceiling mounted to save space. This would provide handle heating and cooling from one "piped" system.

Hydronic heat with "wallbangers" for cooling is another option, but the furnace, "fan in a box," guys have an edge on you when it comes to HVAC in rental properties. Always comes down to $$$'s

hot rod

Andy N._2

radiant condos

I have been involved heavily with radiant condo's and I think it is a great idea. however I would like to give you a few pointers if you don't mind.

1. Definitely do an accurate heat loss for each unit. If you don't have enough floor area to provide the heat loss then use panel rads to make up the difference. Sometimes these condo units have corner rooms with a lot of glass. I have seen problems with these corner units getting to cold and no other solution than retrofitting new mains to heat these areas.

2. If this is a pre-cast building make SURE that the ceilings below will be well insulated. I have seen people spray popcorn ceilings onto the precast above, to save a few bucks. it looks nice and makes sense. This seems like it would not be a problem, however I have witnessed middle floor units at 80 degrees with no control. It takes about a week for the heat to start pushing down from the units above. especially if the upper unit has a thick carpet. remember, carpet is an insulator and the homeowner has a right to put in any type of flooring they like.the top floors are unaware of what they are causing below. This is a big one. be careful of inadvertantly creating radiant ceilings.

3. If you are going to use zone valves go for the quiet models. The taco esp is very loud. these valves will definitely wake people up at night and you will get complaints. also be careful of valves which get installed backwords. they tend to "bang". it is difficult to find the valve which is installed backwords once the tenants have moved in.

4. If you use zone valves in each unit hide them in closets, or other descrete places. don't install them in the open where the homeowner will put the big screen t.v. in front of them. (although I have seen big screen t.v.'s installed in closets.)

5. don't over complicate the control system. remember, if the control system goes down you will probably lose the whole building, possibly even the domestic water. make sure parts are readily available, and it is easy to understand for the average tech. You don't need an outdoor reset control for every riser. If the building goes down it takes about ten minutes for the barrage of irrate home owners to be calling everyone from the G.C. to the president of the association to you. hopefully not the attorney.

6. Make sure you have enough control on the system. This goes against what I said above, however, some homeowners will want shag carpeting while others will have maple hardwood. others yet will want ceramic tile. your system will need to accomidate all of these people. you will probably not be able to speak with each homeowner before they buy the unit and they will not realize the carpet will retard the movement of the heat upwards into their unit. They will after they move in however and at that point it will be your problem because they were not educated on it. This will happen and these people will want heat. This will be your problem. Think two stage heat. think panel radiators, baseboard, convectors or (my least favorite) air handlers.

7. Think redundancy. Instead of one boiler use two. or better yet use four, each with its own pump (primary secondary). Indirect fired heaters? use more than one, pipe each of these with its own pump.(primary secondary). Use two system pumps. each one should be able to circulate the building. keep one as a standby and alternate occasionally. I would pipe the boiler room primary secondary, but do not pipe the system primary secondary. I agree with mark on the parallel return system. usually around here the basement is also the parking garage. You DONT want 100 pumps, valves and flanges out over the 50,000 dollar cars and their paint jobs. think simple, and think no leaks.

8. Make this system easy to vent. once the building is occupied it is VERY difficult to get everyone home at a reasonable time for you to vent a system. put main vents in corridors or janitors closet. dont put them in the top floor units where you can't get to them in a pinch.

9. If you provide the domestic hot water as well, be sure it is sized properly. Dont plan on using priority, because there will be a constant demand. I would get an engineers stamp of approval on it prior to installing anything. remember that these heaters will need to be serviced so make it serviceable. Be sure the recirc pump is sized properly. be sure there is a recirc pump. be sure the domestic water lines are insulated. even a properly sized heater will not work if you dont have the lines insulated. the domestic hot just became a radiator. the end units will not get warm water and the units close to the heater will get scalding hot water. Many times the plumbing contractor will wash their hands of the domestic hot once you take on the responsibility of providing the heaters. The hot water lines MUST be insulated.

10. If you are providing a snowmelt system for the entrys and stairways, ramps, ect. how will you control them? remember, If you need manual control will someone be there to turn it on. will it use a snow sensor? snow sensors will only work if there is moisture present on the sensor. an idling slab is more expensive to run however it reacts instantly and can save you some headaches down the road, or maybe it can save someone else some headaches down the road.

11. Insulate all of your own piping. your piping will become part of the heat load if you dont. The basement and boiler room will be out of control otherwise. the poor tenant over the boiler room will be miserable.

12. remember, there will be areas which you will probably not be installing the radiant floors which will still need to be heated somehow. Think sprinkler heads bursting in the garbage room.

13. How will the cooling be provided? please dont put 80 condensors on the roof. think water source heat pumps, with a single cooling tower on the roof. use hot water coils for your second stage heat or something like that. univents with a chiller would be nice too.

I could go on and on. I didn't mean to write a book here but I feel this is important. I love radiant heat and I don't want to see it get a bad name. one bad condo system affects hundreds of people. One great system also affects hundreds of people. Make sure you build a great system. Be sure you have a reputable designers stamp of approval. a bad system will probably put you out of business, but a great system will build your business. I have seen firsthand all of the problems mentioned above. It is a real heartbreaker.

hope this helps,
Andy N.