pipe coils not radiators, checking edr.

billygoat400

been a good while since here. today replaced a water feeder.

was taking a loooong time for the system to heat up. has 4 sets of piping loops as heaters in an old warehouse building. crane manifolds with 1 1/4" pipe. two 8 pipe runs 110' long, and two 6 pipe manifolds 85 feet long.

one of the bigger ones had the valve closed.

decided to check the edr on these, and came out to 1973 edr based on .75/ft for 1 1/4" pipe. so without a pick up factor 474,000 btu. right?

boiler is 350,000 ish, so think it may be undersized.

original issue was they had to manually feed water since it overfilled a few times. I set the valve to 8 minutes, but when the boiler thuts off, it is taking a long time for the water level to rise, maybe 1/4" in the sight glass after 6 minutes.

I'm concerned of the boiler is undersized, maybe its loosing too much water during operation and it overfills after shutdown. has 2" return line that runs probably 150' from farthest point back to boiler. being two pipe, water may be backing up in lines some as well.

any thoughts on this?

Steamhead

This is a two-pipe system, right? How does the air get out?

dabrakeman

For 1 1/4" pipe (OD 1.66") wouldn't the edr be .434sqft/linear ft?

KC_Jones

https://forum.heatinghelp.com/discussion/comment/1838494#Comment_1838494

This.

With the correct number the EDR is 1206 or 288,440 btu.

If that’s the only radiation you have a pickup factor of ~20% so you have less than typical, but I doubt it’s your issue.

Slow is usually not getting the air out fast enough.

billygoat400

there's modern air vent at end of mains. one at boiler for dry return, other away from the boiler on a wet return.

I misread burnhams heating helper. the basement runs were flat on ceiling, so .71/ft x number pipes. upstrs, 8 row vertical, so 3.52/ ft of coil.

so 1130 edr for 271,200 btus.

billygoat400

thank you.

mattmia2

Where a number of emitters and a main, each emitter is going to start heating at the supply end so they all start heating once the main is hot. with the radiator being a really long pipe, it is going to start heating at the supply end and top and take a long time to heat the pipe and get all the way to the return end and bottom. if they all start heating relatively quickly but take a long time to get fully hot it is working the way it was designed.

billygoat400

I had to go back today. customer said water had filled system up to first air vent again. but this time both boilers in room were flooded.

they were also out of oil. the float gauge was twisted so was showing full when empty.

I'm concerned now that one of the traps may be dirty and condensate not draining well. found a water leak in condensate line in back crawlsapce. water feeder showed added 45 gallons. the other boiler has 725 gallons on the feeder, but not sure how old that one is.

Jamie Hall

It's a very big system — but the basics are still the basics.

And one of those is adequate pitch. Those long long pipes are going to have to carry their condensate to the connection with the dry return. Now are these puppies really loops, or are they manifolded at both ends? I presume from your description — manifolded. So you are looking at 110 feet of pipe for the longer ones. Be very sure that there is adequate pitch on those long pipes — I'd want perhaps three inches, end to end. It isn't much, but… the water does need to flow!

Second, the condensate has to get out. Now — does it go through dry returns back to the boiler? Then you will need adequate pitch on those, too. However, if it goes into wet returns, they do not need to be pitched — but you have to be careful to ensure that there is enough height from the boiler water line to the ends of the long pipe heaters. This is one instance where, while the heaters are warming up, the pressure at the far ends will be very low — very close to atmospheric — so for each pound of boiler pressure the ends of the heater pipes need to be at least 28 inches above the boiler water level or the ends of the heater pipes will flood.

The air has to get out, too — so there needs either to be a crossover trap at the end of each pipe heater into the dry return, or a big main vent at the same location.

Going up one paragraph — be careful of your maximum pressure. This thing may be big, but that doesn't mean it needs more pressure — 2 psig at the boilers is ample.

One further thought. Are these the original boilers? If not, your surmise that they just don't have enough water volume to prevent being drawn down may be correct. If so, you don't need to pump anything — please don't, unless you absolutely have to! — but there might be no harm to a condensate receiver centred on the boiler waterline, and equalized to the boiler mains (not vented to the atmosphere!) to give additional water volume at the water line.