Hydronic baseboard heating system in single story house with a basement runs for 4 minutes then off for 8, consistently until getting up to set temp, which literally takes hours, even for only a couple degrees. Runs longer only on the first call for heat in the morning. There is only 1 thermostat so only 1 zone. I've checked all settings on the thermostat.

The aquastat has HI limit set to 180 with 10 differential and no LO limit because it's heating only, not also domestic hot water. I've bled all the baseboards that have a valve and only water comes out, no air. The radiators in the 2 rooms in the basement do not have bleeder valves. All baseboards are warm/hot, no cold spots that we can find.

I do occasionally hear crackling sounds downstairs at the pipes in the unfinished ceiling that's the living room floor, a little way from the boiler and sometimes at the boiler, that I'm guessing may be air that's not working its way to the valves? There are some blue faucets in the pipes running toward the living room, if that makes a difference.

Any ideas why the boiler reaches the HI limit in only 4 minutes and shuts off, then cools down the 10 degree differential before coming back on and repeating? It does seem to run more "normally" once it's reached set temp. I've mentioned it to the service person for several years when he's here for the cleaning/tune-up and he says this is normal. This is the first year I decided to time the on/off cycles and realized it was that short.

When I ask the service company, they want to bleed the entire system to "reset it", instead of checking to see if all components are working properly. Does this make sense? Definitely expensive at $149/hr. I've decided to try to do more research first.

Oil fired Beckett RSA85LN-TB low pressure boiler,
Beckett by Honeywell R7184B Interrupted Ignition Oil Primary Control,
Beckett Electronic Oil Burner ignitor 746001,
Beckett 21805 burner model K37MYBKN-597,
Honeywell L7224U aquastat,
Taco Cartridge Circulator model 007-F5, (by boiler controls),
Bell & Gossett NRF-22 Circulator (higher up on other pipes),
Lux 9100uc programmable thermostat.

 

Welcome to the forums.

Your thermostat activates the aquastat.
The pump and burner come on together.
The pump runs continuously during a call for heat.
The burner cycles to maintain the 170-180f water.

Is the pump running continuously ?
Is it just the burner that is cycling ?
You should be able to see what's happening with the water temperature by watching the gauge.
It sounds like a circulation problem. It could be airbound causing the pump to pump nothing.

 

The circulators do not run continuously (no idea why there are 2) but I've not watched closely enough to see if they stay on, when room temp is not to the set temp on the thermostat. Forgive me if I sound clueless, but I guess I am. When you say "call for heat" do you mean the entire time until the room is at the temperature I've set the thermostat for? Or do you mean each time the thermostat clicks and the boiler responds?

I will try to watch that tomorrow morning. When I was watching before, it was the numbers on the aquastat, gauge and thermometer I was concentrating on, though I did notice the pipes on both sides of both circulators were vibrating; the one right at the boiler more so. Also, all the pipes I can get to are hot except the one that I'm assuming is the water intake.

Unfortunately, the gauge is very hard to watch because for some reason it's under the aquastat. I do know that it seems to read about 8 degrees cooler than the aquastat.

 

Justcantdoit heating system problems is due to old technology boiler temperature control aquastats.
Dealers keep them for long term service profits.

Homeowner’s easy, low cost solution is with $186 aquastat and $12 auto vent valves.

Modern Tekmar 256 aquastat with 1F degree control, live display of actual temperature, menus for hi low settings. Also has saves up to 20% on fuel cost with out door reset.

https://s3.amazonaws.com/s3.supplyho...-submittal.pdf

https://s3.amazonaws.com/s3.supplyho...56-install.pdf

https://www.supplyhouse.com/Tekmar-256-Boiler-Control-One-Stage-Boiler-4150000-p\

Unvented/bleed air in system makes noise and reduces heat transfer. Solution is installing $12 Watts auto vents at high points of each zone, Are very reliable, easily opened for service. Has black knob on Watts to manually check, confirm venting or turn off. https://www.supplyhouse.com/Watts-05...Vent-3679000-p

Longer run to morning day time temperature setting is normal.

 

It is not uncommon when coming out of thermostat night setback for the boiler to hit a setpoint temperature and turn the burner(s) off. The pumps run continuously until the setpoint temperature is satisfied. After that all would shut down until the thermostat demands again. If this is happening the boiler is more than likely oversized, zoned or both.
How may thermostats do you have?

 

The OP said one thermostat but two circulators.
That could be DHW (domestic hot water) tank setup.

Calling for heat means the room temperature is under the set thermostat temperature and the system should be in heat producing mode.

A few pictures of your system would help us to help you better...... How to insert pictures.

 

Is he also saying no DHW? I'M confused by his comment.

 

Boiler was new in 2009 when we bought the house and there's only 1 thermostat. Yes, I understand it's normal to take longer in the morning when first on

rbeck: I think you're saying, regardless of whether the HI limit has been reached and the burner turns off, the pumps should keep running until the temperature set on the thermostat has been reached? I ended up not being able to listen/watch for that this morning, but hopefully I can tomorrow. Any idea why there would be 2 circulator pumps?

I'm not sure whether you're referring to setpoint as HI limits on aquastat or setpoint as set temperature on thermostat, or both.

doughess: Sounds like you're thinking there's a problem with the aquastat? I know its been replaced once since we lived here. Or are you suggesting the aquastat with outdoor reset in addition? Would that make a big difference in WV?

Wouldn't adding valves involve a plumber?

Does anyone think bleeding the whole system at $149/hour and expected half a day to to it seems excessive? Is that the logical step before diagnosing other problems? We have a contract that covers a lot of parts, but not bleeding the whole house pipes of water...

 

Sorry, I see you both posted again while I was composing a reply. Hopefully these pictures help and I can get more if needed.

 

It does appear that the circulator stays on until setpoint is reached. I also experimented with changing the Hi limit differential from 10 to 15 and it extended the run time from 4 to 5 minutes and the off time from 8 to 11 or 12 minutes. Does this indicate anything?

 

It looks like you have pumps on both the supply (red) and return (black). It that correct? Do they both run at the same time? Usually two pumps on a single zone system (only 1 thermostat) indicates a primary/secondary system with closely-spaced tees. (Usually high-efficiency condensing boilers.) Not often used on an atmospheric boiler like yours. Your piping does not look like a P/S system.

Setting a larger differential causes the boiler to stay off longer after hitting the set point. That will extend the OFF time since lower temperature water will be circulating. And will cause the run time to be longer to make up for starting at a lower temperature. As long as the water temperature is enough to provide a satisfactory level in the heated space, longer run times are better to avoid short-cycling. However atmospheric boilers should not be run below certain temperatures (usually 130-140 degrees) for extended time to avoid condensing. My Burnham ES-2 boiler is designed to run as low as 100 degrees, I run it at 150 degree set point with a 30 degree differential on a large mass cast iron system that can drop to 100 when starting at 120.

AFAIK the stub-out on the supply pipe near the lower flange of the red pump does not connect to anything? The connection above it appears to go to a loop not connected to the red pump. If so, that loop will be getting flow due to the black pump. Could this be a system that had one zone/loop with a pump on the return and a two loop addition with a supply pump?

 

I'm honestly not sure if the red pump is vibrating less than the black one or if it's not actually running and just getting vibration through the pipes from the black one.

I have noticed that it gets a bit cooler in here after changing the differential, but assume it would be better for the whole system? When we first got the house, the old thermostaat, a honeywell, had no problem getting the house to set temp. I'm not sure if this started (taking hours to increase a couple degrees) when we replaced the thermostat when it stopped holding it's programming, or possibly later when we had no heat and ended up having the aquastat replaced.

I'm sorry, I don't understand what you mean in your last sentence. I've tried to follow the pipes and can't tell what goes where. I have been told the system is set up weirdly. Do you need more photos? If yes, of what?

 

This looks like a separate heating loop that gets flow from the black pump on the return line.

Have you tried listening for pump operation by placing the tip of a screwdriver on the pump and the handle against your ear?

 

The supply pipe with your red circulator has a yellow ball valve on top of the pump and then the pipe splits to 2 feeds with a throttling valve on each pipe which I believe are only 3/4's open. Those valves adjust with a flat screw driver to open fully. You can loosen the nut a little if needed to bre able to turn screw and then retighten. You want thay line straight up & down for fully open going in direction of pipes.

This will give you more flow to your emitters. The 2 pumps are unusual. Do you have any idea why 2 were installed.

 

The installation is not properly installed no matter where the pipes go. There should not be one pump on the supply and one on the return. If in fact there are two zones and someone disconnected a thermostat an connected both pumps to the same pump terminals the piping is incorrect.
You are going to have to see where the returns come back to the returns. They are all above the return.
I see the supply manifold or what ever it is has another pipe off it. Where does it go?
The pump on the return (black) is the arrow pointing down? The red pump arrow point up?

 

It's a maze of pipes and I don't know how to tell what's coming and what's going. Do these pictures help? I have no idea why 2 pumps.

If the red pump is sending hot water through the house, my guess is the branch to the right is going toward the kitchen upstairs and the one off to the left is going down the hall toward the bathrooms upstairs. The one behind the branched pipes that goes up and to the left against the wall goes around the corner and toward the upstairs living room, but splits into 2. The pipe that's behind and above the split above the red heading to the right, doesn't appear to be attached into the boiler pipes at all but must be somehow because it's warm. That's the direction of the far side of the living room. I have no idea how hot water gets to the 2 downstairs rooms but they are the same direction as the pipes to upstairs bathrooms.

This is how the pipes were when we bought the house in 2009. I know that for years it heated the house fine, but the last several it has not.

I have not tried listening to the red pump with a screwdriver but know it does vibrate, just much less than the black one right at the boiler.

On the horizontal pipe at the top.of the pipe that is vertical above the black pump there is an arrow built into the pipe that says 'water' and points toward the elbow.

I hope any if this makes sense. I tried to answer all questions as best I can.

 

Also, how do you heat water for sinks, showers, etc.? Separate water heater? Electric or gas?

Have there been any changes other than the thermostat?

ABSOLUTELY NOT!!!!!!!! After we figure out how your system works you should consider getting a new company. Or at least tightly managing what they do to "fix" things.




Unless the system pressure is low this is not causing your problems. What is system pressure when boiler is off for a while? What is pressure when boiler has run for some time and is hot?

If you cannot read gauge, see Sticky at top of forum about pressure gauge.

Supply is the vertical pipe next to the red pump (water flowing up). Return is the vertical pipe above the black pump (water flowing down). Each branch/loop should have a connection to them but pipes could be combined along the way. Best way to understand is to think how the water will flow from supply to emitters to return. Every pipe that goes up to an area or room should have a pipe that also comes down even if there are additional branch connections made between them above.

Water can be pumped into emitters (i.e. red pump) or away from emitters (i.e. black pump) but should not be both on the same system.

 

You have a SUPPLY pipe coming off the TOP of the boiler going into your RED pump. That pump is sending water through a TEE fitting to 2 pipes which go to emitters and then return to the RETURN pipe with the BLACK pump. You also have a third supply pipe with the green or black handle valve that comes off the main supply after the RED pump which means that line is controlled by the BLACK pump on the return line.

Unless I'm missing something, what I'm seeing from your pics is the SUPPLY coming off the top of the boiler, feeding those 3 supply lines, up to an elbow and going to the extrol tank and to the BLACK pump and back to the boiler. Is that correct or does it separate somewhere as it should.

 

aquastat cover removed

 

Spott: I think you are correct. I missed that.

It now looks like a weird version of a primary/secondary system. (Without the second pump, I would have called it a bypass.)

If p/s it could work like this:

Black pump is primary. Water circulates through supply “manifold”, through air scoop and back to boiler. Return from emitters is connection with green valve that passes behind red pump and connects to “manifold”. Red pump is secondary circulating through double connection to emitters and back through return connection. Short section of manifold pipe between red pump stub out and return stub out is bypass and may be acting as “closely spaced tees”.

Primary circulation could account for short cycling. I will research further for p/s system on atmospheric boiler.

This suggests that it is not an appropriate application of p/s.

 

Domestic hot water is a separate electric hot water heater.

It does sound like (with the screwdriver trick) that the black pump does run, though it's hard to tell if it's just the pipes vibrating from the red pump.

Aquastat was changed several years ago, but unfortunately the service company records didn't include the year on that service order, just the month/day. I had asked them to send me records a couple weeks ago and they've migrated to a new system so don't have details on all. In Feb '20 the transformer was replaced, so I think it's a safe assumption the aquastat was before that.

I see in late Feb '18, we ran out of fuel and they had to bring us 10gallons. It looks like they filled dank next day and a couple days later,they came back about a noise and noted air in lines, changed the tank from top fill (that the previous company who placed the new tank said was better because it wouldn't grab gunk from the bottom) to bottom feed which of course was at a hefty fee.

I also see in Sept '21, they used a .60x80A nozzle instead of usual .75x80B. The only other one listed on the burner label is a .85x70B

 

 

From the last picture seems like you are correct, just a very poor attempt at it.

 

rbeck: Poor attempt at which?

 

This is the gauge after boiler has been off 1.5 - 2 hours for night setback. Aquastat says water temp is 103 degrees. Is it concerning that it looks like there's water inside the gauge and it's below the aquastat?

 

That has to be the worst attempt at a p/s piping setup as I've ever seen. With the sysytem you have there is no need for it or even a bypass is not needed. You would do yourself a service if you redid the near boiler piping and you would most likely get more heat.

With the air scoop on the return pipe above the pump I doubt that air vent is even doing anything with that pump pulling so much. You can put extrol anywhere but the air scoop goes on supply.

You should use the nozzle that is called for, at least the spray angle and the spray pattern. Your burner wants a .85x70B. The 70 is the angle and the B is solid spray. The .85 is the gallon per hour it dispenses. You could go down to a .75 if you thought the boiler could pick up quick enough but .60 I believe requires another head on the burner. The head has fins that allow only so much air. Your head I believe is an F3. A.60 requires an FO head in order to burn properly. Your burner sticker says .85x70B YET the boiler OEM specs say .75x80B @ 140psi pump pressure.

Your nozzle is pretty important on your boiler because it's a steel boiler or dry base as they're called. If the flame hits the firebox and ruins it you have dry steel behind it which could burn through.

Sometimes you can take those covers off. Dry it and keep an eye on it.

 

I assume you mean dry the gauge?

If it makes a difference, I just came across info online that indicates what I've been calling baseboards, are actually fin-tube convectors.

Wouldn't redoing the piping be very expensive, especially with copper tubing? I have no idea who installed the system but there's a good bet it was the flippers we bought the house from. A lot of things are wrong with it that were hidden. On the other hand, they may have just taken out the very old-looking boiler that was still in the basement when we first saw the house, and slotted in the new one.

Is it possible the installer tried to make it so changes could be made in the future?

I actually convinced the service manager come out and see what he can do and he said he will look at everything and will let me know before he has to charge me.

I'd pointed out I've mentioned the very slow heating for several years and the usual tech just keeps saying it's fine. I told him with the gold contract, I don't feel I should have to pay to fix things that may be worse because of not being addressed when I originally mentioned the issue when the tech was here for tune-up/cleanings. I also pointed out that I have records showing they have been out here in the past without an additional fee, and not just the free yearly tune-ups that are included in the contract. They redid their contracts this year and they also raised the price another $100.

I told the service manager the tech that called me last week (different from the usual by my request) before coming out for my appointment that took about a week to get, and after asking me what's wrong, didn't get back to me for a day or 2, that their idea of bleeding the entire system to reset it seemed excessive, even if there is air in the system that's not coming out at the baseboards upstairs.

I pointed out how it's been running inefficiently for years, costing us a lot more fuel than it should have, as well as not being as warm as we used to be.

I did tell him I've working with people online and doing a lot if research, and he didn't think an outdoor reset would be beneficial here in the Eastern Panhandle of WV. I do like the idea of automatic air removers, though, and may order some to have on hand before he gets here. I also ordered 3 different replacement thermostats if needed (I couldn't decide which). We know we don't want wifi or touchscreen thermostats but do want 7-day programmable, with early recovery mode.

Service manager is scheduled for next Wednesday afternoon and they will let me know if there is a cancellation and he can come sooner.

Sorry to babble on ..




This looks more like what we have


I've apparently been using the wrong word when I say we have baseboards.

 

This is the gauge shortly after turning off during a cycle when already at thermostat setpoint.

 

justcantdoit: When there is heating issue, one of the first, simple things to is confirm venting of air at high points of zones,

Photo in Post 17 shows auto venting valve above expansion tank. Venting valves or manual/purging at boiler level cannot remove all air in high elements of many systems. Those valves often leak and have to be sealed off.

DH Post #6 outline easy, long term venting:
Unvented/bleed air in system makes noise and reduces heat transfer. Solution is installing $12 Watts auto vents at high points of each zone, Are very reliable, easily opened for service. Has black knob on to manually confirm venting or turn off.
https://www.supplyhouse.com/Watts-05...Vent-3679000-p

 

Thanks to Spott for addressing the issues so clearly, especially the nozzle. Oil is not in my expertise.

Not really, especially if you DIY it. A professional would probably not do it as follows but a fairly simple DIY solution would be:

• Remove red pump and replace with a flanged nipple between the existing flanges and valves. Since the valves are there this could be done without draining any water.
• insert new valve on vertical pipe between supply and return stub outs. Could be Shark-bite, soldered copper, or copper compression. Keep valve closed to isolate supply and return flows. Again by closing supply and return valves the amount of water to be drained to do this work can be minimal and limited to the area of the near-boiler piping. Draining and/or flushing the system should be avoided.

This will cause all the water to flow through the emitters (convector or baseboard does not matter) and should improve the timing of heating the space.

This does not address the air scoop issue but may be satisfactory once air is purged from the system by bleeding (NOT flushing). Moving the air scoop to the supply side will entail more piping work and would eliminate the need for the suggestions above.

If not DIY get some quotes or suggestions from your service company or others and come back for our opinions.

Your gauge readings look OK. The hot pressure reading is approaching the 30# limit. If it goes over then the safety valve will open to relieve the pressure. That will result in a discharge of water to the floor but not a flood.

For the time being, I suggest you use a 180 degree set point and 10 degree differential to keep the water going to the convectors as hot as possible. Also use overnight setback temperature of not more than 3 to 5 degrees less than daytime to reduce recovery time.

 

So put the differential back to the 10 from where I'd changed it to 15?

I like the idea of those vents, as mentioned previously, we have no plumbing skills and I'm not sure we can get to the baseboards to replace them.

I also can't figure out which piece you're referring to as the air scoop.

Since this started several years ago, I stopped setting the heat down to 62 and only do 64 now. I also only let it go up to 66 during the day instead of 68 that I used to. When more than 1 person is home earlier than usual, I bump it up to 68.

For the first 5-10 years that we live here (hard to remember when this all started), the system had no problem with 62 night and 68 day.

So the info I see online elsewhere showing flushing the system every 5-6 years like you should do yearly on a household water heater, and what the service company wants to do, is incorrect?

I appreciate all the help you've been giving us.

 

Flushing a closed system is not required unless you have a water quality problem. See Sticky at top of Forum list.

Water heaters only need a few gallons drained to clear deposits that may accumulate. I’m not sure that applies to electric since there is no combustion involved.

 

I've looked at the stickies and don't see one on proper way to bleed it. Does just adding those air vents do it? I sometimes hear "crackling" at the boiler and other times near the pipes heading to the living room in the ceiling of the basement, that I assume is air bubbles moving. I also hear the metal fins in the baseboards making noise sometimes, especially in the bedroom, the furthest point from the boiler, but assume it's normal.

Are you saying the venting valve above the expansion tank may be a problem?

So these suggestions you've all made should fix the fact that apparently something stops the water from leaving the boiler fast enough, which makes the burner shut off in only 4 minutes before setpoint is reached?

We don't have plumbing skills ourselves, so would have to get estimates. I'd get some of those valves to have on hand before the service manager gets here if I knew how many I may need. Maybe a different aquastat as well, in case that's the problem. I'm waiting to see what he suggests and what he's willing to do, but I'm trying to learn as much as I can before he comes.

 

Sticky: Do not flush

Crackling noise is not a problem unless it is IN the boiler. Other noises from pipes, fins, enclosures is usually expansion/contraction of the metal—not a problem. Air in system will sound like gurgling. Bleed at convectors as you have been doing if necessary. As long as you get water from convector vents air is not a big problem.

Small cap on top of vent above expansion tank should be opened one turn. You may hear air coming out. (Looks like cap on a tire valve.). If it leaks close it tight.

Don’t throw money at parts (including additional air vents) you may not need. Take time to determine what should be done and get estimates. As long as you have heat, winter is not the right time to make changes.

 

So don't do anything yet except put the differential back to only 10 and open that valve? Do I turn it clockwise or counter-clockwise?

 

Correct. Also consider raising overnight setback temperature for quicker morning recovery.




Also, when bleeding both here and at the convectors make sure the pumps are not running.

EDIT: On second thought, since the air scoop is on the wrong side of the pump you should NOT leave the cap open. Just open it to bleed air and then close it again.
​​​​​​​

 

justcantdoit: When you open faucet, flush toilet, take a shower there is little noise from water flow in pipes. Noise when heating system water is circulating is largely due to unvented air in the water.

For many reasons both homeowners and professionals do not confirm of venting by open vent at high point of system until only water and not air comes out. Instead of doing simple, easy check first, they go on timely, complex wild goose chases that do not resolve problem.

Watts auto vents work well. They may not be "PROPER" way for some. On DH home system they have worked GREAT for many years.

 

The auto-vents definitely sound useful, but we'll have to hire someone to install them and it sound like the piping needs rearranging anyway. The only problem with that is that the system worked well for years.

Anyway, does any of this address why the burner only runs for 4 minutes and off for 8, taking forever to get to setpoint?

.I am aware of the typical metal sounds but that's not what I meant when I said "crackling" - this sounded different.

I do have the service manager coming Wednesday afternoon, but know even though he said he will do what he can, at some point he will have to charge me. I know that many parts, unfortunately not the aquastat, are included free in the contract we have, that ends end of March.

 

Boiler is short cycling because the water in the primary loop heats up very quickly and is recirculated to the boiler reaching the boiler set point quickly. A small amount of water is pulled into the secondary loop to the emitters but because of the volume it heats up much more slowly and therefore takes longer to satisfy the thermostat.

If the piping was a loop (not primary/secondary) all the heated water would go to the emitters and return cooler to the boiler. The boiler would run longer each time to heat the larger volume of water.

The total run time of the boiler and use of fuel would not be much different.

 

Thank you for the explanation. Why would it have worked well for years then stop working? The piping has not changed.