Quietside boiler-Radiant problem

BobbyG

thanks for the reply Chris! The written loads (15,000 & 75,000 btu's respectively) are the heatloss calculated for the rooms.

With the secondary tees being close, I thought flow in secondary shouldn't effect flow in primary. The temps (on the drawing) show the flow is coming out of boiler into first zone (75,000) btu's and then out of it and into the secondary (15,000) zone and then back into the boiler. I didn't know the boiler pump was only 3-5 gpm the secondaryzone pumps are sized normally but don't know what is happening with the primary (boiler) pump. Thanks for the input!

BobbyG

I am having a tough time figuring out what is going on with this system. After much discussion with the boiler "quietside" people I found out the pump in the boiler is supposed to produce 3-5 gpm only. (Sounds like delta T's are Ok with P-S flow and loads)

Problem 1. Homeowner is using too much propane. 80 gallons in a week. We have had lows at design temp. during this week. But load only 90,000 btu's at design load. 0 degrees

Problem 2. boiler shuts down for 10 minutes after running 20 minutes and t-stat still calling for heat. (not usual suspects-hi-limit, air press switch, etc.)

While I was there today, the boiler ran (low fire)for 3 hours (see problem 2)and raised the temp on the t-stat only 1 degree. (70 to 71 degrees and we moved the t-stat up to 73)

I have written specifics of system on picture, if you have any other questions, please ask away. Thanks for your help, it is greatly appreciated!

Frank_3

New fangled toys

Ignoring all the water temps, flow rates, and pipe sizing issues for now, here's what I found in the owners manual for the FR-5 thermostat:

"Unoccupied (Energy Saving Mode)"

"The unit runs automatically for 20 minutes then stops for the selected time; this cycle is repeated until the occupant returns home and de-selects this setting"

There's also a note that the "stop time" is set in increments of 10 minutes.

So, I'd say the fancy thermostat is programmed wrong.

It looks like you have to press the middle button in order to put the thermostat in "room temperature" mode. If you press any other button after that you will switch it out of that mode -- tell the homeowners to stop playing with the buttons when you're not there. :-)

BobbyG

Thanks for the input. We are only using the "fancy" t-stat for the boiler output setpoint. For t-stat zone control we are using a nix pump ctllr with the "end switch" going to the boiler signalling the need for heat. I'm pretty sure everything else is ok. I will check if this feature is still functioning when not using the "fancy" t-stat.

What do you think about the propane use?

Thanks Again!

Frank_3

Propane use sounds right, actually.

First, you have to understand that all I'm working with is the online copy of the Quietside QVM9 owner's manual. I've never touched one of these things, seen one, nor care to.

I'm not exactly sure which model of the QVM9 series you're using, but the manual shows the series can use between 4.23 and 6.01 lbs/hr of propane. So, if we take 20 minutes on and 10 minutes off and work that out over a 24/7 week then the math tells me the unit would be running for 112 hours, or it would consume about 560 lbs of propane. Considering that the unit probably doesn't run 24/7 all week and with the outside temperature being so close to design limits then I'd say 80 lbs/week is pretty reasonable.

Back to the fancy thermostat. If you're using it to set the heating output temperature the manual shows me that the left button needs to be pushed (and lit up). If your customer decides after you leave that he wants "energy saving" because he thinks the propane usage is too high, then I'd say there's a good chance somebody messed with the buttons. Particularly since you mentioned the unit was cycling 20 minutes on and 10 minutes off, which precisely matches what the owners manual says will happen when it's in "energy saving" mode.

Frank_3

Ooops.

I just re-read your original message and you said 80 gallons per week of propane, not 80 lbs/week.

There are 4.2 pounds of propane in a gallon, so that means your consumption is about 336 lbs/week. Again, still within the 560 lbs/week that the math tells us the unit would use if it were running 24/7, with 20 minutes on and 10 minutes off.

Herb

propane use

Propane at 91500 BTU's per gallon could be a reasonable consumption if there are other variables accounted for. Is the water heated with propane, clothes, fireplace, etc. Also the company may have packed the tank with more than a normal fill. Was a leak check performed with the completed system not just your slice of the pie. Good luck Herb@Gibbs Gas Service.

Chris Maderia

I'm confused

There are 2 things that have me scratching my head.

Your first loop you state you are delivering 15,000 btus 6gpm @ 10' head. The number's just don't jive.

GPM = BTUH divided by Delta T x 500

In this case your Delta T is 9 degrees. That means your GPM is actually 3.3 GPM not 6 GPM. If we go by your figures you would actually be delivering 27,000 btu's at 6GPM not 15,000.

Your second loop you state that you are delivering
75,000 btu's. You have a 26 degree delta t. That means your GPM is actually 5.77 GPM not 10 gpm. Again going by your figures you would be delivering 130,000 btus at 10gpm not 75,000.

How many BTU's is your heat source? Maybe here lies your problem. Just a thought.