Commercial chillers so cold, even a penguin will reach for a blanket
There are two main reasons that recovery rooms struggle to keep their ice bath cold, even though on paper they've done everything right.
I'll cover the power rating in next weeks newsletter, but this week I'll talk about the heat load going through your pools.
When you're trying to figure out how many people go through your cold plunge, the easiest metric is the number of people to come in and out of the facility per day.
100 people came through, therefore 100 people went through the bath.
But the issue with that, in a single session most people will plunge 2 to 3 times.
So that hundred people all of a sudden turns into 200 or 300.
Sauna Use - 50% more
The majority of users will do contrast therapy.
They'll go from sauna or the hot pool into the cold plunge for 2-3 cycles.
This adds roughly another 50% heat load per plunge. Heat load being the body heat added to the water.
So now that 100 per day is looking more like 300-450 heat loads.
What does this look like in numbers?
An average 80kg person over a 3 minute plunge in 5 degree pool adds .55kw of heat.
100 plunges per day means 55kw of heat load.
That's manageable.
But add the extra plunges (2–3 per person).
At 0.55kW of heat added per plunge, now you're looking at:
And that's before factoring in contrast therapy. If the majority of people are going from a hot sauna or spa into the cold, they bring in even more heat per plunge—about 50% more.
So:
That's 3x to 4.5x more heat load than the original 55kW you might've expected from 100 users.
A lot of numbers - but what does that mean for the users?
In a 1000 litre pool, that's 10.8 degrees celsius increase in temp that your chiller can't remove until the evening, if at all.
When you're sizing up a chiller in the future, always take this into account.
It's the difference between a crisp 5 degrees, and a not so crisp 15.8.
Next week I cover why most chillers on the market are under half of their advertised specs.