Steam to Liquid Heat Exchanger

The Balancer

There is an expansion tank. The liquid is glycol.

But how come the pressure does not increase when I use the other HX?

The Balancer

Steam to Liquid Heat Exchanger

Problem. We are working on a Taco Steam to liquid heat exchanger. As the steam control valve opens, the system pressure on the WATER side increases to 100PSI and then a relief vavle blows.

Any ideas as to why this is happening?

Thanks

Tony Conner_2

You're...

...putting way more heat into the system than it's rejecting via the heat emitters. Is the circ pump running?

It's great that there's a relief valve on the liquid side. You wouldn't believe how many HXs I see with NO overpressure protection on the cold side. They're bombs.

The Balancer

I thought of that. But there are two HX's in a lead lag situation. It does not happen with the other one. The pump is running. Everything remains the same in each HX, except the water pressure increases when the one HX is used.

Could it be leaking steam into the water side?

Tony Conner_2

In Most...

... installations like this, the liquid pressure is higher than the steam pressure. They normally leak from the liquid side into the steam side. What about the temp control valve - is it sensing the increase in liquid temp & cutting back the steam flow properly? Even if there's a leak, the steam valve should throttle-in as the liquid temp approaches the set-point.

All the liquid valves are open, right? (Ask me why I always try to remember to check the easy/stupid stuff early on...)

Blackoakbob

Flow thru the HTX.....

is critical when the steam is applied. Tony is right to ask about the basics ie. are the valves open, did someone leave a plastic plug in the piping, is the relief valve the correct pressure rating? That happened to me this summer, I didn't check the relief setting and what a surprise! Best Regards

thp_8

What is your

steam pressure, what is your normal water side pressure?

The Balancer

Pressures

The steam pressure is 15psi. The water side pressure starts at 30psi and increases to 90-100 psi.
The steam control valves to back down, maintaining a water temp of 180. The return temp is around 170. There are two valves, a 1/3 valve and a 2/3 vavles. The 1/3 valve opens first and then the 2/3 if it needs to.
The water side pumps have a VFD, operating around 38HZ. There is a differential pressure valve so there is constant flow in the system even if there is no call for heat. The head across the pump does not change throughout the pressure increase.

The thing that is interesting is that there are two HX's. This pressure increase only happens when HX-2 is used. Under identical conditions, the pressure increase does not happen when using HX-1.

Thanks for your help on this.

EBEBRATT-Ed

What about an expansion tank on the liquid side of the system????

When the liquid heats it will expand hence the pressure build-up
ED