Direction of flow Primary loop versus Tees

Garfield

Closely Spaced Tees. Does it matter which way the water is being pumped? For example if the water is going down on the right side of the loop but your secondary loop circulator was circulating the water in the opposite direction requiring the water to go up for that few inches?

Jamie Hall

up and down doesn't matter. Quite irrelevant. What does matter is that the supply Ts are reached before the return Ts in the primary loop flow direction.

mattmia2

You want to pump the supply water out of the primary loo downstream of where you return it otherwise you are largely just circulating the water in the secondary loop without mixing it with the primary loop.

Garfield

Thank you for the advice. I confirmed that my close spaced tees were installed in the proper direction after all. 

08GeezerGlide

Does the primary loop always need to have a circulator pushing or pulling within the loop itself? Crazy question but I seem to have come across this somewhere.

hot_rod

There are a number of way to pipe a primary loop. The first one I consider the boiler within the primary loop. Close tees could be added anywhere along that loop.

In the series primary loop, last pic, think of the loop as a conveyer belt just circulation round and round. With close tees energy can be put on the belt or removed off the belt. One challenge with either of these series is the temperature keeps dropping along the loop at each set of tees. The last set of tees can never get the same temperature as the first as it runs.

Two other examples where the loads are in parallel instead of series, so each zone will see the same temperature. There will still be temperature blending in the close tees depending on flow rate changes between loads and boiler input, but all zones will see that same blended temperature.

Garfield

hot_rod said:

There are a number of way to pipe a primary loop. The first one I consider the boiler within the primary loop. Close tees could be added anywhere along that loop. In the series primary loop, last pic, think of the loop as a conveyer belt just circulation round and round. With close tees energy can be put on the belt or removed off the belt. One challenge with either of these series is the temperature keeps dropping along the loop at each set of tees. The last set of tees can never get the same temperature as the first as it runs. Two other examples where the loads are in parallel instead of series, so each zone will see the same temperature. There will still be temperature blending in the close tees depending on flow rate changes between loads and boiler input, but all zones will see that same blended temperature.

Thank you for taking time. Is it relevant the velocity difference between the two loops?  I can re pipe but it would be considerable expense.  

hot_rod

The whole premise PS is to allow varying flow rates between the two loops. And at times there may be reverse flow between the closely spaced tees. When the boiler flow exceeds the secondary, some flow goes the opposite direction so the boiler maintains the required flow rate

A drawing of what you have or are proposing may help

Garfield

The last diagram, you posted - figure 5–8 it’s identical to that, except for I have substituted in the instinct boiler for one of the loads with closely spaced tees. 

Garfield

After looking everything over, I think I need to re-pipe it.  I have a Triangle Tube instinct 199,000 BTU boiler to 2 separate 5” x 12” 100 plate heat exchanger’s.  One of them is for the carwash anti icing floor heat so needs to put out glycol between 60 and 100° depending on how cold it is outside.  The other exchanger is for hot water for the car wash 125° is what we usually have the water set at.  I’m tempted to just use one boiler pump, and Pumps are both Exchanger’s and the Boiler.  There are already separate pumps  on the load side of the exchangers. 

mattmia2

Is ~200,000 BTU enough to hest the water for a carwash?

hot_rod

Some of the last car washes I worked in only use hot water to mix soaps, everything else was cold water. RO water for final rinse.

Garfield

We use hot water for the self serve except rinse. I want to size this piping so I can add another boiler if necessary.  This is enough heat on all but the busiest days.  When it’s cold enough to need a lot of floor heat, it’s not very busy.