Pressurization problem

DYI2day

I have a small 2 loop slab radiant floor located 7ft above my manifold/ heat source system located in the basement. 

The loops were pressure tested to/from the manifold(s) holding 60lbs for 2 days. 

I was able to fill the system with water- no leaks and limited flow using a Grunfos Alpha2 pump. 

I have no pressure and no source of pressure being a closed system. 

How has this problem been addressed?

GGross

if you are shooting for 18 psi (for example) you need to fill the system to 18 psi. If the pressure drops, as you say to zero, then you have a leak

Jamie Hall

Do you have an expansion tank on the system? If not, you need one. Not optional.

DYI2day

Here’s the kicker. Because it’s a small system and I’m on a budget I elected to use a 28 gallon electric hot water tank heater. I changed the pressure relief valve from 150 to 30 lbs. 
When I attempted to push more water into the system using a1/2hp transfer pump water escapes through the hwt’s pressure relief 
I was wondering if a small pressurized (15lbs) water holding tank gravity fed into the return side of my hwt is a feasible solution?

DYI2day

I have an expansion tank @ 14lbs

GGross

@DYI2day

what pressure did you fill the system to? if water came out the relief then you went over 30 psi. if you fill too close to 30 psi you run the risk of that pressure climbing ever so slightly and blowing off the relief.

hot_rod

Those transfer pumps can move a lot of flow quickly, maybe use a valve to slow down the flow from the pump. It will pump more than you can purge out through a basic washer hose, so pressure climbs quickly.

Jamie Hall

DYI2day said:

I have an expansion tank @ 14lbs

That should be a big enough tank, assuming it's set up right. Disconnect it from the system and drain all the water out. Now set the air pressure at the Schrader valve to 14 psi (or whatever you want). Now reconnect it to the system,, get the air out of the system, and adjust the cold system pressure to 14 psi.

If you have no leaks, it should hold the 14 psi cold almost indefinitely, and perhaps rise as high as 20 psi when the system is hot.

DYI2day

It’s a closed system- no cold water supply pressure 

DYI2day

I can’t honestly say what pressure I filled the system too though I have to assume it was just over 30lbs  for the hwt’s pressure relief valve to let go. Hot_rod’s right about transfer pumps pushing a lot of water fast. I’m gonna try it again with a speed control on the pump. Heat the water and monitor it. I could use the pressure relief valve’s release and/or the manifold purge to release water and pressure. Sound workable?  Thank you all!

hot_rod

Ideally you have the purge valve full open as the pump runs. If you are pumping into the system through a purge valve, regulate the flow with it. You should be able to adjust the pump flow in to match what you purge out without exceeding 30 psi.

The Webstone purge ball valves work well so you can adjust flow. Boiler drains are not ideal, easy to pop the washer off when you flow backwards into them with that amount of flow.

GroundUp

If your 30# relief is blowing, you have 30 pounds of pressure at the relief. Anything below that will have a higher pressure. WHy are you saying you have no pressure? The only way to add pressure is to add water, which it seems you are doing. What does the pressure gauge say, and what is the actual problem here?

Jamie Hall

May I add that it is my preference to replace a pressure relief valve which has operated -- that is, opened -- once the problem which caused it to operate has been fixed.

EdTheHeaterMan

I am wondering why someone would design a radiant system with no pressure gauge and no temperature gauge. How are you going to know when to stop adding water when you get to the proper design water pressure? What is the design water temperature for the radiant floor? at least you were bright enough to install a pump.

Try this:https://www.supplyhouse.com/Bluefin-TDB25-75-BK-2-5-Tridicator-1-9-16-Well-Back-Mount-Temperature-Pressure-Gauge-0-75-PSI-30-Degree-to-250-Degree-F