Loop system hot-water heating Q&A

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Loop system hot-water heating Q&A

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toasty1

If the boiler is located downstairs, should I route the water tube upstairs, entry or downstairs first? (1 example- going from the boiler (that's located in the basement) going upstairs first then going back to the boiler in the basement).

DanHolohan

You want the hottest water (the supply water) to go to the room that has the greatest heat loss, and then continue on from there.

mikes112

We have a hot water radiator system and when the boiler first comes on I hear water running through the pipes. We never heard this years before. Once the water running sound is over then its quiet. I guess the pipes have fully filled with water? Or whats happening? How do we fix this?

rick in Alaska

You have air in the system. Check your pressure gauge first to make sure pressure is up. Typically 12 pounds. Most likely you will have to manually bleed air out to get the noise to go away. If the pressure is low, and you can get it back up, and you have the right air separator, it might take care of itself.
Noise in the system like that means you are also not transferring heat as efficiently, and when it gets bad enough, the heat will stop moving. Need to get it fixed right away.
Rick

Estelle

I have a question, I just bought an old home that has baseboard hot water heat...according to my licensed HVAC guy (I have used this company for over 20 years in my other homes) there is water in the boiler, but it is not there at all times..we have experienced it mostly after a good rain. Even the HVAC guy says he does not understand why it is not there at all times. He does say that there HAS to be a crack in there somewhere causing this issue and that the boiler needs to be replaced before it lets go and floods the boiler and kills it. He says the only way to find the crack is to totally take the system apart, but that he is sure there is a crack and we need a new boiler. Is there any other thing that could be cause this water in the boiler or do you agree it should be replaced? Thanks for your help..it's getting wicked cold here in Maine so if it does need to be replaced we need to get it done very soon.

hot_rod

It would be wise to find the leak before replacing anything. If it is in the boiler that should be visible. An over night pressure test should determine if it has a leak.

A new boiler on a potentially leaky piping system will be a problem.

heatingcustomer

I just got a hot water radiant heat system installed with fin style baseboard heaters. It took a really long time for the house to heat up, but more importantly the rads never seemed to get really hot. Is it normal that the rads should NOT get really hot? I'm used to cast iron rads that you can barely touch. The house did eventually heat up and is comfortable but it tool a LONG time - like around 8 our so hours.

Jamie Hall

heatingcustomer said:

I just got a hot water radiant heat system installed with fin style baseboard heaters. It took a really long time for the house to heat up, but more importantly the rads never seemed to get really hot. Is it normal that the rads should NOT get really hot? I'm used to cast iron rads that you can barely touch. The house did eventually heat up and is comfortable but it tool a LONG time - like around 8 our so hours.

This is not the same system as we've been talking about before in this thread? You might have better responses with a new thread just for this...

However, as a first cut, are the baseboards and the radiant on the same zone? And is it floor or ceiling radiant? Radiant floor or ceiling runs at a much lower temperature than the baseboards should run, so if they are on the same zone you are going to have real problems. Further, radiant floors or ceilings will take a long time to heat from one temperature to another -- 8 hours is quick; I've seen days, depending on how big the change is.

RustyK

I have a multifamily property with a single boiler hot water baseboard heat. Each apartment has a pop top valve with a thermostat. In one studio apartment the heat sporadically stops working. Once 2 years ago the pipe burst. The water will stop flowing sometimes, usually on cold days here in Wisconsin like 5 degrees or below. At the boiler each apartment has its own piping, it's not a single loop system. I've changed the valve and bled it many times. Yesterday it stopped when the apartment was still 60 degrees. There was some cold air coming through the wall by the inlet and outlet (where the pipe goes into the floor) so I used foam to seal those cold areas. In areas, the pipes go through the room inside the concrete flooring. If the boiler is working and the building and other apartments are warm why would only one apartment have this issue? Is it the cold draft hitting the pipes? Any ideas why 0-3 times a winter it stops working?

DanHolohan

It could be that the flow isn't balanced and the water is going slow enough to freeze.

Burd

Good day.
Our house was built in 1958 and we have the original hot water heating system. Many radiators are imbedded in troughs in the floor along the walls with grates covering.
It is a two-zone system with two thermostats and two water pumps.
Each zone has it's own water cut off valve.
I have leak between floors and I will need some demolition to access the leak. That is in the works but not for another day.
Meanwhile, for leak control I turned OFF the thermostat for the leaky system to let the zone cool down.
Then, I turned off the water supply TO JUST THAT ONE ZONE.
But, I still have the leak.
(And, the water is cool, just fyi.)
I presumed that it might just be the zone continuing to drain but it has been several hours and it does not seem to be slowing.
Any suspicions regarding this continuing leak? Zone just not yet drained?
Where would any other water be coming from if the feed valve is closed?

Any suggestions would be appreciated.

Burd

Jamie Hall

I think you will find that closing that valve closed off flow to that pipe -- but that the other end of the pipe is connected to the returns. Or the other way around. In any event, closing that one valve did not close both ends of the loop. Therefore, it will continue to leak until the water level in the system drops to the elevation of the leak.

Sorry about that.

Your solution temporarily is to drain the system down to the point where the leak stops.

Burd

Thank you! That sounds like what we got here.
Where I have access to the leak I am able to direct the water and control it. If I just let it continue on it's own will the level eventually reach th leak and 'stop'?

Jamie Hall

Burd said:

Thank you! That sounds like what we got here.
Where I have access to the leak I am able to direct the water and control it. If I just let it continue on it's own will the level eventually reach th leak and 'stop'?

yes

Jlove95

I'm not real familiar with our boiler system yet but our house is over 3000 Sq. Ft. We have 4 zones, 1 of which is not heating. We noticed that all of the pipes coming from the zone valves are hot but 1. Can anyone tell me what would cause this?

Jamie Hall

Air in that loop. Zone valve defective and not opening. Zone valve OK, but not receiving power. For starters.

PaulD

On my loop system, if I restrict the flow on the return will that make allow us to maintain more heat at the end of the loop?

Brewbeer

No, restricting the flow through the loop will result in even cooler temps at the end of the loop. Increasing flow through the loop will help keep temps at the end higher.

jumper

How much cheaper is one pipe over two pipe? Especially when you consider that you need bigger emitters down the line?

PSL

I have upgraded to HVAC/heat pump and no longer need the closed-loop system. I would like to remove the pipes and covers. Can I cut the pipes off with a hacksaw, and or should I do an additional step prior to that to ensure that the water is no longer in the pipes. The water was heated with an oil burner furnace which was removed from the house.

Jamie Hall

I hope you are in a warm climate. Otherwise, you'll wish you had left the system in place.

However, in answer to your question, just drain it out and hacksaw away. If there was antifreeze in the system, the water which drips out here and there should be mopped up immediately... it's not really toxic (except to pets) but even so.

Canucker

Am I the only one that laughs when looking at the selection of used cast iron rads available with "upgraded to forced air" in the description?

Jamie Hall

Canucker said:

Am I the only one that laughs when looking at the selection of used cast iron rads available with "upgraded to forced air" in the description?

No you're not! But the part of the description which makes me laugh is the "upgraded" part. Right...

MattNunes

I have a closed Loop System and am trying to figure out challenges to Hot Water through the Faucet and Shower? Temperature is 180 on the Boiler Thermostat and we keep the Zones about 68 degrees, would turning the Temperature up on the Boiler Thermostat provide for greater amount of Hot Water available on demand? BTW the Site is very informative. Thanks

mcpascaln

Its the first time that I have heard about thermostatic radiator valves, or TRV, a self-contained, non-electric zone valve. I am curious, how much does it costs to install one in a closed loop system?

nicholas bonham-carter

Are you having a problem which you believe needs a TRV?
They are a bandaid of last resort, and you are better off finding out what problems your system may have, which leads you to believe that you need TRV's.
Can you describe the symptoms?--NBC

JonDC

Some help please: I have a 1950’s hot water 2 loop system. It worked fine until recently, when the first floor open design was sluggish. Then the ceiling sprung a leak - we found an old “air scrubber?” Not sure what it really is , it is the size of a steam radiator valve with a screw cap on top. It is in the attic at the start for the second floor loop, it was open and dripping down to the basement! As soon as it was replaced and closed up the first floor loop jumped back to normal hot. Is this attic component necessary? Should I just take it out and put a plug in the fitting? And why was it ever used. There is an air scrubber on the supply side of the boiler and mounted on top of that is another one of these “do-hickeys”like the one in the attic. The boiler is new 10 years. Oh and Ive read and rebuilt my steam system in my other house using TLAOSH that is running great now after 20 years ! Now, I want to go through and check my hydronic system fully. Jon

Jamie Hall

That air scrubber probably was the expansion tank for the system. You either need it or a modern bladder type expansion tank hooked in at the inlet to the pump(s).

JonDC

Not sure about that Jamie as there wouldn’t be room for an expansion tank the elbow is right up against the wall and lath and the connection is on the elbow and is 1/4 inch. The riser comes up and turns right into the wall. There is a bladder expansion tank on the supply side of the system, I’m not there right now but I think it’s ahead of the scrubber in the basement near the boiler. There is another identical “do-hickey” to the one in the attic , it is at the boiler mounted on top of the air scrubber. Its about the size of a steam radiator valve with a cap that screws open or closed.

LiBrown

We have two-zone hot water baseboard heat. The downstairs loop has a thermostat in the dining room and the upstairs thermostat is in the hallway at the top of the stairs. How can we get both zones to operate at the same time? Usually if the heat is set to 70 degrees downstairs, the upstairs loop shuts off and the bedrooms are cool. At night if we lower the downstairs loop to 60 the bedrooms get heated to 70 but downstairs gets cold and led to a frozen pipe. Would it help to move the upstairs thermostat out of the hallway into one of the bedrooms? Can both zones maintain 70 simultaneously? We were told our new furnace is big enough to heat the entire house. We have a natural gas furnace but had the same problem with both an oil furnace and an older gas furnace.

Jamie Hall

@LiBrown -- you'd do much better to start a new discussion thread on this. But to answer your question, if the two zones are truly independent each thermostat should control one zone, and the boiler should run as needed to heat either separately -- or, if both thermostats are calling for heat, both together.

You can check this very easily: start with the whole thing off. Turn one of the thermostats up to, say 75 or so. It's zone (but not the other one) should start to heat and get nice and warm As I say, the other one shouldn't get any heat. Now turn that thermostat back down and let things cool off again. Now turn the other thermostat up -- it's zone should get heat, but not the other one. Turn it back down again and let things cool off again. Now turn both thermostats up. Both zones should get heat. Turn them down to where you want them.

If any one of the above checks fails, you have a controls problem. Something isn't wired correctly, but we'd need to know a good bit more about the system to figure out what.

Let us know what happens...

BillShaine

Does closing the damper or dampers or using a bypass valve save energy or just rebalance the heat. We have guest rooms that are rarely in use, so we are trying to figure out whether we can shut them off on a temporary basis the way we did when we had electric baseboard heat.

DanHolohan

If you shut the dampers on the baseboard the room will definitely be cooler. Whether that's good or bad depends on where the thermostat for that zone is.

BillShaine

But does it save energy to close the damper?

DanHolohan

Yes. The room will be colder. Rather than transfer its heat to the air in that room, the water travels to the next room at a higher temperature. The result is the water returning to the boiler is hotter than it would be if all the dampers were open, so the burner doesn't have to heat the water as much as it would if all the dampers were open. That saves fuel.

BillShaine

Which works better, closing the damper or using a bypass valve?

DanHolohan

I would just close the dampers. It's simple and doesn't require any piping.

BillShaine

Thank you! This is very helpful.

Eli87

Hi. I have hydronic baseboard radiators. My floors are being redone and I’m trying to find out how much space is needed between the bottom of the cover and the floor to allow airflow. An answer would be so appreciated!

DanHolohan

An inch will be fine.