Water temp

[luke123]

Hope someone can help me, Have a customer in which they have about 15 water source heat pumps on a water loop with no boiler to heat the water. Water is fed and cooled from a tower and holding pond and also serves to cool many other water cooled machinery. Now the return water tempature from the entire loop varies depending on the # of differant equipment it is currently serving and outside air temp. Supply Water temp is recorded sometimes as low as 39 dg. during shutdowns.

So obviously I am having problems with freeze protection lockouts (carrier RHR060 units) when the water gets cold and units running in heat. Any suggetions ?(besides adding a boiler)

Also,water has no additives for freeze protection.

[maxster]

if you have dedicated WC units that aren't HPs and cooling only....refer boxes ,straight cooling units 24/7 that is your only SOURCE of HEAT.work the tower fan if you have control there to keep the fan on it off as long as possible to build up your supply to the WSHPs.you need to have a load coming off that tower that the WSHPs can see as aload when there in the heating mode..right.if you can add up all the straight cooling loads or machinery that will heat the tower water for your HPs and the compare it to your HPs total and work that tower fan...can you bypass the holding pond that will drain your heat build-up your trying to make for your loop in the heating mode.

[lolson]

add a boiler

[luke123]

Thanks for the help. At this time I don't believe I can bypass holding tank, But I will look into it further. I see where your going here though by using cooling water return to raise temp. Maybe some sort of 3 way mixing valve?

[maxster]

try to keep that tower fan off as long as possible so what heat is coming from those water cooled straight A/C units can be used to temp up your WSHPs loop.

[Bill Tappin]

no way to cheat physics. your going to need a way to add heat to the loop,PERIOD. as for water treatment the same rule applies.

[dryguy]

Instead of a boiler, you might be able to get by with a small water-to-water heat pump designed specifically for those low temperature days to feed warmer water to the loop.

[luke123]

Thanks for the suggestions guys, Lately I have been thinking of some sort of tankless water heater to heat up the loop. Maybe have it cycle it off and on according to water temp? don't know if it would work just throwing it out there.

[aNtHoNyNoZ]

this might be a little extreme but how about some heat trace cables with a temperture controller and a relay whatever

[orion242]

this might be a little extreme but how about some heat trace cables with a temperture controller and a relay whatever

Extreme...nope...1/2 a$$ yep!

You should keep the loop between 100F-60F typically. 39F I can't imagine any of those units are going to be running for long.

Sounds like they have change things since the design. If the water cooled equipment cannot keep the loop warm, you need another source of heat.

[michael26]

You say that you have "water cooled machinery." You really ought to consider adding a 3-way valve and using the heat produced from the machinery to heat the hp loop rather than trying to get rid of heat through a pond or tower. I would think in the Oregon winter that you would only be cooling the loop more by running through a pond. Is the machinery heat load constant, to rely on it for the heat. Try the 3-way if so if not then add the boiler but it sounds like you need the 3-way regardless.

[luke123]

You say that you have "water cooled machinery." You really ought to consider adding a 3-way valve and using the heat produced from the machinery to heat the hp loop rather than trying to get rid of heat through a pond or tower. I would think in the Oregon winter that you would only be cooling the loop more by running through a pond. Is the machinery heat load constant, to rely on it for the heat. Try the 3-way if so if not then add the boiler but it sounds like you need the 3-way regardless.

Thanks for the help. The heat load on the water is not constant, When machinery is running their seems to be no problems it is only during shutdowns of machniery for maintenance that water temp gets that low.
I am begining to think that they must add a boiler to solve this problem.