Temporary heat

Earthfire

KISS principle. spa pack and spa pump will control filtration circilation and heat and has built in heat. 450 gallons is a small spa by todays standards. Available from most spa or pool dealers ( Leslies, etc.)Use some dow strofoam insulation to cover the tub between shows to control evaporation

Steve Paul

Temporary heat

is required for a small, on stage pool that will be used for a show that will play about 5-6 weeks in a local stage production. The pool will contain about 60 cubic feet, 450 gallons or 3750 pounds of water (your choice). The pool installer will provide chlorination and filtration. We have been asked to provide heat for the water that the actors will be dipping their feet into.They want the water to be maintained at approximately 80 degrees. The room temperature may go down to 60 degrees between shows.
My mission should I accept it, will be to provide a means of supplying the heat. I am thinking of a 40 gallon electric water heater set at a high limit of 120 deg. A Taco 007 circulator at the bottom of the tank "pushing" the return pool water back into the heater, and discharging the hotter supply water from the top of the tank back into the pool, with flow control valves on both the supply and return lines. This system will not be under pressure because it is open and only under atmospheric pressure. In fact I will be adding a 15Lb. pressure relief valve in addition to the standard 210 deg./150 Lb. PRV (overkill?). The Tank will be maintained at 120 deg. The circ. will be controlled by a reverse acting Aquastat set at 80 deg. That will control a 24V relay to turn the circ. on when the pool temp. drops below 80 deg.
My questions:
1- Does this sound safe and reasonable?

2- Is a 40 gallon water heater, constantly on at 120 deg. going to give me the potential 20 deg. temp rise that I require?

3- What is the Wattage conversion factor to BTUs?

4- Does anyone have a better plan or suggestions?
Thanks in advance for your help.
Steve Paul

scrook_2

what's...

the local plumbing inspector's take on the W.H. as a "pool heater"?

The 15psi in addition to the T&P is probably overkill in the open system, but it can't hurt (assumint the water from it and the T&P are routed to a drain pan or somewhere else harmless) and they are cheap to buy

1 kW is 3413 BTU/hr, so a 4500W W.H. yields just over 15k BTU/hr.

Could you get an "over the side" electric immersion heater/drum heater/etc. instead with enough wattage at a low enough price to heat it directly (removing it for the shows & filling w/ warm water initially so as not to save the long initial warm-up)? Look at Chromolox or Watlow for example.

is an 007 overkill? (or you could just throttle it as req'd)

Is the pool chlorinated/brominated? Will this eat up the H.W.?

Mad Dog

Without doing any calculations

that seems insufficient to heat that water to 80. Mad Dog

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Grumpy

You have a 75,000 BTU load requirement. That is equivalent to 22KW. If the water heaters were below the pool elevation then you might have fewer problems trying to do this with water heaters. Since there is a chemical (chlorine) involved, you should really be looking at using a stainless steel heat exchanger to protect the heating unit. I'd use a JASS LT075 pool heat exchanger and an Argo AL24S electric boiler. Those two items plus the pumps, controls, etc., you will have at least $2500 in material costs alone. Might be overkill for the limited time of the show's run. Maybe a very small swimming pool heat pump would be a better option?

Joe C

Temp heat

We just did a two day boilier swap and used a 150mbtu propane torpedo. Fan forced,thermostatically controlled,ez to set up and not to expensive to rent.Used 100# of propane for 2 days.

jim lockard

May be

A couple of wet suits for the actors? Oh yea whats the electrical inspectors take on a couple of Electric Water heaters with or without ground fault protection and how far is the stretch on the approved for.Best Wishes J.Lockard

Grumpy

Hmmmm?

How were the CO levels in that place?

Jim Miller

what about a set up like is used in church baptismal tubs? - spa pump for circulating the water in the tub has electric heat in the outlet side, has a flow switch so the electric heat stops if the pump stops - they use these to heat the "dunk tank" which , I think, is larger than what you are talking.....

Joe C

OOPs

Sorry responded to wrong post.4 Screeming kids in a phone booth. Should have been attached to elect heat post .Unoccupied building.

Mark Eatherton1

Time...

is on your side. Yes, it is a 22 KW load, but over what time frame? If the basic load is raising the water from 60 to 80 degrees, then the 75K btu is correct. If the pool is kept hot, you only have to overcome the standby losses of the pool. If the pool is covered, and the walls are well insulated, actual standby losses are probably nil. If the load of maintenance is 1/4th the load of pickup (typical) then you'd need 5.5 KW to do the job, and it would take you 4 hours to recover from 60 degrees to 80 degrees, which requires just a little bit of preplanning.

JM$0.02W

ME

tombig

They're Actors!!!

Tell 'em to act like it's warm for crissakes.