Radiant Heating Pump pulling power, 0 GPM output. Advice Appreciated

Pheraph

Good morning,

Figures right as it gets cold the Radiant Heating System stops working. Looking at the Pump, it is pulling power and I can hear it spinning faster if I turn up the speed. But it is only putting out 0-1 GPM according to the reader. Looking at some other posts they say there could be air in the system. I had the pump replaced a year ago, so I think it should be fine. I believe the red valve above the pressure gauge is for purging the system correct? If I drain it, do I need to refill it from another source or will it pull directly from the water heater? I haven't done this myself, but I am confident I can after verifying some things. Anyone have thoughts or suggestions before I start? Any help is appreciated.

EdTheHeaterMan

I see a ThermXtrol tank that is rated for an open system and comes pre-charged with 50 PSI air pressure. It is connected to a closed loop system that operates at less than 10 PSI according the the gauge pictured. That is a mismatch that can have air problems associated with it. Do you know what the air pressure in that tank is right now? can you test it with a tire gauge?

If that diaphragm in the tank has failed, the air that was in that tank may be in your piping right now. To get the air out, you must know what the pressure on the ThermXtrol tank is, that it has not failed and that it can be adjusted down to 12 PSI. Otherwise you need to get an Extrol #15 tank https://www.supplyhouse.com/Amtrol-101-1-15-Extrol-EX-15-Expansion-Tank-2-Gallon-Volume that is made for that system. Then you need to have a water feed valve to add water to the system, an isolation valve to force the water to go thru the loop(s) then exit at the purge valve you indicated.

hot_rod

I think you have a combi cor heater. It has a coil inside so the potable water and heating water is separate. I don’t see air purger on the system, so ongoing air removal may be a problem.

Also it looks like you have to connect a garden hose to fill, purge or add water. You might try putting the pressure to 18 psi to see if it starts flowing. Bump the pump to speed 3 can move air also.

It’s a pretty bare bones system. No air purger, pressure relief valve, purge valve.

Dave Carpentier

Can you feel a temperature difference between the 2 pipes going up thru the ceiling ?
What is the GPM if you put it on speed 3 and give it a min or so to settle in ?

Was the GPM reading different when you replaced the pump last year ?
The ability of the pump to circulate is dependant on both the loop resistance and the pump's design range (pump curve). Pumps have to match their load, approximately speaking. Could it be a bad choice for pump ?

EdTheHeaterMan

I would like to add to this: Just because it worked for some time before the failure, does not mean that it is piped correctly, what it does mean is that the mistakes are finally catching up to you.

Pheraph

EdTheHeaterMan said:

I see a ThermXtrol tank that is rated for an open system and comes pre-charged with 50 PSI air pressure....

I don't have a tire pressure checker unfortunately. Ill need to pick one up. It used to have higher PSI reading after being installed initially.

Dave Carpentier said:

Can you feel a temperature difference between the 2 pipes going up thru the ceiling ?
What is the GPM if you put it on speed 3 and give it a min or so to settle in ?

Was the GPM reading different when you replaced the pump last year ?
The ability of the pump to circulate is dependant on both the loop resistance and the pump's design range (pump curve). Pumps have to match their load, approximately speaking. Could it be a bad choice for pump ?

After setting it to High, the temperature on the pipe going into the ceiling feels like it is hotter than before. The reader is still showing 0-1 GPM. I don't recall what it was last year after being replaced, it was higher though. And the pressure gauge reading was higher as well.

Video below shows what the pump sounds like.
https://youtube.com/shorts/RALVLULN_EA

It wasn't this loud before.

EdTheHeaterMan said:

I would like to add to this: Just because it worked for some time before the failure, does not mean that it is piped correctly, what it does mean is that the mistakes are finally catching up to you.

Also a possibility, I would need to hire someone to verify the setup I guess?

While looking at it found this thing on top of one of the pipes, is it a gas/air relief valve or something?


Also noticed a small puddle of water coming from base of the water heater, not sure if its a leak or condensation build up?


Thank you for your replies, I appreciate it.

hot_rod

Looks like a lot of water from condensation.
However, if you have a large heating load, you can pull the temperature down low enough in the tank that they will sweat and condense. And the hot water temperature to the house will drop also.

Kinda limited to what you can pull out of those combi tanks, I think the burner was 65,000 BTU/hr X 75% efficiency so maybe 48,000 BTU,hr.

What type of heat emitters do you have? Low temperature radiant concrete slabs will really drag them down.

Pheraph

hot_rod said:

Looks like a lot of water from condensation.
However, if you have a large heating load, you can pull the temperature down low enough in the tank that they will sweat and condense. And the hot water temperature to the house will drop also.

Kinda limited to what you can pull out of those combi tanks, I think the burner was 65,000 BTU/hr X 75% efficiency so maybe 48,000 BTU,hr.

What type of heat emitters do you have? Low temperature radiant concrete slabs will really drag them down.

Not sure what type of emitters, and not sure how to check. Is that the tubing that is under the hardwood floor or something in the water heater?

hot_rod

Fin tube baseboard around the rooms?
Cast iron radiators?
Radiant heat in the floors?
A box with a fan inside blowing hot air?

Pheraph

Radiant heat in the floors.

Pheraph

Last year when a company replaced the water pump they purged the air first from the bottom valve. I just don't recall how they refilled the system with water. Looking at this setup, how would one go about filling it up if I were to try to purge the air myself?

EdTheHeaterMan

I looked at the instruction manual for a Bradford White Defender water heater that has the two side tappings (pipe connection holes) and found there may be a system that must have all components to be compatible with potable hot water. Even the space heating side of the system requires the components be compatible with the opens system water.

THE FOLLOWING INSTRUCTIONS ARE FOR INSTALLATION OF
GAS WATER HEATERS SUITABLE FOR WATER (POTABLE)
HEATING AND SPACE HEATING
1. All piping components connected to this water heater for space heating
applications must be suitable for use with potable water. In Massachusetts,
space heating piping length must not exceed 50 feet.
2. Toxic chemicals, such as those used for boiler treatment, must not be
introduced into potable water used for space heating.
3. This water heater must not be connected to an existing heating system or
component(s) previously used with a non-potable water heating appliance.
4. When the system requires water for space heating at temperatures higher
than required for other means, such as an ASSE approved mixing valve
must be installed to temper the water for those uses in order to reduce the
scald hazard potential.
Please refer to the illustration below for the suggested piping arrangement.
This seems to indicate that this is not a Combi-Core® tank with the internal heat exchanger that @hot_rod mentioned earlier. However the pressure gauge indicates the there is a heat exchanger coil attached to those side tappings. If you could provide the model number of that tank, then we could tell exactly what in on the inside of that tank. If that is the heat exchanger type, it is piped incorrectly. If it does not have the internal heat exchanger, then the piping might be fine.

EdTheHeaterMan

Once we know the type of tank, we can better help you to get the air out of the system.

hot_rod

Get two 6 or 8 foot long washer hoses. Connect one to the bottom drain on the water heater, flush some water for a minute to get clear clean water. Connect that hose to the bottom purge valve Valve 2

Just above or below the pump is a brass shutoff valve. It takes a large screwdriver or maybe an Allen wrench. Turn it 1/4 turn. This stops flow, forces water one direction.

The other washer hose connects to the top valve to purge out of. Valve 1

So water goes into the bottom purge valve, around the system, can’t go by the pump which you shutoff, so out comes air and water, from the top purge valve.

Purge into a plastic bucket with the hose submerged to see the air bubbles. When they stop, turn the upper valve off slowly, let pressure go to 15-20 psi. Shut off lower valves. It can take 5 minutes or more to clear all the air out.

Another option is to get a small sump pump, many of the small plastic pumps have hose connections. This type you toss into the bucket.
put it into a 5 gallon bucket, fill it and pump into the bottom valve. This will be slower, but easier to control😏

EdTheHeaterMan

Here is a better illustration of @hot_rod"s diagram. This shows the radiant floor tubing not in the picture. The instructions are the same. Close valve at the circulator pump (#3). Attach the hose from the water heater darin to #2 purge valve. let the water out at #1 purge valve.

Once that is all done, close the valve #1 first.
Then close the valve at the bottom of the water heater second.
Next close the valve #2
Now open valve #3
Check the pressure gauge. if the water pressure is over 50 PSI (or 115 feet) lower the pressure to about 20 PSI or so by letting some water out of valve #1. Then you should be good to go for the rest of the winter. .


By the way.. you still need a relief valve and other components on that heating system closed loop, if it has the heat exchanger coil inside the tank. Please let us know the model number so I can determine if you have the Combi Core® or not.

Pheraph

Looks like it is Bradford White Combi2 TTW
Model # CDW2TW50T10FBN

Pheraph

Looking at my setup, I don't see the #3 valve above my circulator pump. Just a strait pipe.

hot_rod

Above and below the pump, do you have a component that looks like this? If so it is a shutoff valve to isolate the pump for service. Basically a ball valve that uses a screwdriver to operate, and maybe an allen wrench.
Or use to purge.

Pheraph

Oh, yep! There is one above and below. Thanks.

Pheraph

I think I did it right, there was a good amount of air pockets in the system as I was purging it. Closed everything up at around 25 PSI. After running it a bit and the tank heating back up, the pressure rose up to 50 PSI. Should I reconnect the hose to valve #1 to relieve some pressure? or will that put air back into the system? Do I need to go back through those steps in order again? Also while purging it, I saw where the water came from earlier. Might need to tighten one fitting prior to the 3 way, not sure about the other that's on top.

hot_rod

15- 20 psi is adequate. There should really be a 30 pressure relief valve on the system to prevent over pressurization.

Pheraph

Something like this?
https://www.homedepot.com/p/Wilkins-3-4-in-30-PSI-Relief-Valve-P1000AXL-30C/304571741

EdTheHeaterMan

Yes exactly like that one .

EdTheHeaterMan

I looked at your model number on the Bradford White website and found that you DO have a heat exchanger coil inside that water heater as @hot_rod mentioned. That means the the relief valve for your water heater is not in any way connected to the Space Heating Closed system. You should have a separate 30 PSI relief valve along with a Extrol 12 PSI expansion tank for closed systems The one you have is for open systems and has 50 PSI pre charged air pressure. Wrong one, but if you lower the pressure to 12 PSI in the tank when disconnected from the water pressure of the system, then you should be OK.

If I were using that system in my own home I would also add a water feed that is permanent that way I don't need to connect hoses to fill and vent the loop(s) every time. You could just connect a hose to the purge valve.

Illustration to follow:

Pheraph

I lowered the PSI to around 12 .

@hot_rod @EdTheHeaterMan Thank you both for your knowledge and assistance. I was able to purge the air and get my heat working again. The circulator still shows 0-1 GPM, but I am starting to think that is normal since my house is heating up. Saved me a lot of money, and I learned a lot. Favorited this thread so I can review it later if needed. Is installing a relief valve pretty easy? I look forward to your next illustration.

hot_rod

I would remove this purge valve and install a brass tee there. Add relief valve and drain valve there.

If you are a risk taker, pinch off the Pex to the left of the tank, shutoff the pump iso valve again, drain from the upper valve and install tee. Then you would not lose much fluid.

Or drain down, since you know how to purge now.

ethicalpaul

If you are a risk taker, pinch off the Pex to the left of the tank

Another advantage over copper!

EdTheHeaterMan

Here is the updated illustration:


There are 5 changes I would make if I lived there, when the season is over.
1. Relief valve 30 PSI. located at the top of the copper pipe with the circulator. That is the easiest place to put it. A better location would be at the top outlet of the heat exchanger supply pipe , (lower left end of the Red PEX Line in the illustration)
2. Add a micro bubble air eliminator (just above the expansion tank)
3. Add a permanent fill valve with backflow preventer and auto feed valve.
4. Add a Purge station to the left of the Micro bubble air eliminator (I labeled the purge station with the number 1 and 3 so you can use the same Purge instructions, but you don't need to use the washing machine hose to connect to valve #2)
5. Remove the air vent from the top of the other copper pipe. It is just about the most useless location for that vent.