Baseboard heaters do not heat. Is there a kludge/hack/pump to get by? Direct return (corrected).

eclecticmn

I am a homeowner, not a plumber. There is a limit to what I can do. I recently replaced some steel pipe near radiators with O2 barrier pex to valve them off and make flooring work easier.

I do not know things like temps and pressures and flow rates and do not think I have gauges for that except for a pressure gauge that reads maybe 18 psi. So I cannot answer questions about that.

I have a 1915 farmhouse in the middle of a city in MN with hot water heat and many cast iron radiators over two floors and slantfin baseboard radiators in the kitchen. As far as I know the kitchen baseboards never worked. I thought it was a plumbing problem and replaced the old beat up units and gate valve. No help.

The copper pipes going to the baseboards do not get hot. Experiment. Last year I turned off every radiator in the house and the copper go too hot to touch.

I am pretty sure I have 1 1/2 steel (what kind?) pipe in one of the two main lines with a 3/4 tee going to copper going to a ball valve going to the baseboards. I am not going to drain the system and mess with anything before the ball valves this winter.

1. Any ideas on my situation?
2. Is there a problem with the main line sucking pressure out of the kitchen loop?
3. Is there a way to put a pump in line on the supply or return after the ball valves? That would get me by. I guess I would wire it along with the existing pump control.
4. If I wanted to install monoflo valves next year what kind of work/hell am I in for? The existing tees are in the middle of a long run. How would I handle that?

EBEBRATT-Ed

We would need pictures of the boiler, pumps and the older piping and newer piping

eclecticmn

I can take photos when time permits. The steel pipe is covered in massive insulation so not much to see. The point is that only the kitchen baseboard heat does not work. All other cast iron radiators got hot.

Jamie Hall

Would it be possible for you to make a diagram of how the system is piped? What goes where and how it gets there? It is not really a problem of sucking pressure out of a loop -- that really can't happen -- but what it is that something about the way the piping is arranged is such that the water -- which is very lazy -- is taking the easy way to get around, and that easy way doesn't include those baseboards. But without seeing at least a diagram of the piping, it would be almost impossible to say exactly why.

Actually one simple possibility is that those radiators are simply air locked -- but it may be very difficult to get air out of them.

Monoflow Ts (not valves) are very unlikely to help any.

mjstraw

I have a similar problem.  Someone removed the CI rad from the kitchen and replaced with fin tube baseboard.  Used same connections (last ones) into the mains as the original rad.  Two pipe direct return system.  Kitchen baseboard never gets warm.

I've decided there's little flow thru the baseboards, and since the rest of the house is so over-radiated, the boiler rarely reaches hi limit (180).  Baseboards like really hot water.  And the lazy water prefers easier paths thru the rads earlier in its path.

My planned attempt to correct is to move the kitchen to its own zone.  May end up short cycling the boiler.  We'll see.

eclecticmn

My radiators are fed from a main line and return through a different main line so that one large main line is supplied from the boiler and one large main line returns to the boiler. My slant fin is fed as one of the first units and the radiators further downstream work fine. I will post a diagram and photos when time allows.

What does short cycling the boiler mean?

eclecticmn

I removed some pipes and checked for blockage. None. So plan B. The 1 inch off the tee used to reduce to copper then to the baseboards. No they go to a 1 inch ball valve so I can fix this later. Maybe find some local under window cast iron radiators.

Steamhead

eclecticmn said:

Maybe find some local under window cast iron radiators.

That's your best bet. Try to match the capacity of the old rad, and use the same size pipe as the original. And don't use PEX, as the fittings restrict the flow.

eclecticmn

Thanks to all. I will think this through. One issue is that the concrete wall in the basement is either 6 or 9 inches past the kitchen wall, depending on the wall. So, either I put the radiators real far from the kitchen wall or place them closer to the wall and run the pipes on the floor for people to trip over or place the radiators close to the windows and run the pipes over the floor under that radiators to the corner (where no one will trip) and have them turn to extend out and down. I chose the last approach. So they extend out where I could later hide them under some box.

Long ago I posted my problem and gave up.
Previous owner had 3/4 copper and slant fins that provided no heat.
He could not find a solution so he put in a wood stove! It is cute but takes up lots of space plus the clearance so not many cabinets.

I moved in and the slant fins were beat up and had paint on them.So i replaced them with new slant fins which did not work either. I once got them hot only by turning every other radiator in house all the way down. I found him and he told me his story. So no central heat in MN kitchen for 24 years now.

I got some advice but most made no sense. There was no air lock. One said that the 3/4 pipe was too small. Maybe. I expected corrosion or blockage in basement. I got mad and ripped out the copper and slant fins. No corrosion or blockage. THEN someone suggested putting a circulating pump in that loop only. Too late.

I decided to try putting in cast iron radiators and found some over the years but had bleeder valve problems.

I will post a diagram below. There are 2, 2 1/2 inch supplies and 2 returns. Only 1 thermostat in the house and no current way other than individual manual radiator valves to control anything. I replaced those when I moved in because they were stuck open or shut. I have no idea what a lock shield is.

The kitchen loop in the diagram WAS 3/4 copper, reduced down from 1 inch by a bushing right near the 2 1/2 main. I cannot swear that all pipe sizes are accurate but the 3/4 inch was. I would be happy with something one step above a wood stove. Only half kidding.

https://i.imgur.com/YNUIjTO.jpg
https://i.imgur.com/FXwlkGR.jpg
https://i.imgur.com/abGgA56.jpg

mattmia2

I'd suggest you connect the baseboards separately to the boiler with their own supply and return pipe and circulator. Put flow checks in each loop (the old system and the new loop to the baseboards to prevent ghost flow). Put a separate thermostat in the kitchen. Even if you can get flow in the baseboards they will never heat the same as the cast iron radiators. The CI will heat and cool slowly and the baseboards will heat and cool quickly. They will work far better on separate zones.

eclecticmn

Thank you. After I got mad and tore out the baseboards and copper I inspected them all expecting blockage and found none. Some plumber from White Beak Lake MN made a similar suggestion over the phone except I recall he only said to add in a circulator pump for that loop. That would steal more hot water from the rest so he said maybe put in a gate valve after the pump to control that. I think he visited one of these forums.

All this advice is very high level for me. I realize that you professionals have to control the temp in each room or sub unit and that was never the case in this two story 1915 farm house. There is no sign any professional has set foot in this house after the initial radiator and pipe sizes were selected. I suspect some non professional removed radiators once and threw in the slant fins.

EdTheHeaterMan

In order to help you get a better understanding of how the old radiators work and how the new baseboard radiator work here is a simplified diagram of a heating system with some numbers added to visualize in your minds eye what is happening. At the bottom of the illustration there is a complete Monoflo® system. Heat circulates starting at the boiler, then it goes the the radiators then the lower temperature water returns to the boiler to be reheated.

In the upper picture in the illustration one of your radiators will take a small portion of the heated water from the main pipe and circulate into the radiator to heat the room. The pipe on the other side of the radiator will return the colder water back to the main pipe at a rate of less than 0.5 Gallons Per Minute (GPM). When someone redesigned the kitchen with a copper tube/alum fin type baseboard, they messed up the pressure drop across the supply and return pipes of that radiator. That made the amount of water going into the radiator less than the original design.

Since the new radiator requires a large flow rate (at least 1.0 to 4.0 GPM) the water took the easier path and decided not to go thru that new radiator. It is all physics and you can't break the laws of physics.

So basically, that radiator needs its own circulator pump to make it work on your system. Either design will work, home run or adding a small pump the the existing pipes. I believe the home run idea is better, but if that is not possible, then add the small pump to what you have.

It is unfortunate that you needed to learn the hard way, because this has been known by pros for over 70 years. But now you know and you can move on from there.

Good luck with your project.

Mr. Ed

mattmia2

eclecticmn said:

I am pretty sure I have 1 1/2 steel (what kind?) pipe in one of the two main lines with a 3/4 tee going to copper going to a ball valve going to the baseboards. I am not going to drain the system and mess with anything before the ball valves this winter.

I think it is separate supply and return mains, but the resistance of that fin tube loop is still far more than that of a ci radiator.

eclecticmn

Thank you. I asked for a lot of advice on line back then and even paid a monthly service for on line advice for a month or two. Got lots of advice but none as good as yours or some others on here. One piece of advice was that I should not mix slant fins and cast iron on the same system/circuit/whatever. I know now I should have at least tried the circulator pump in line.

BTW my system has 2 sets of mains, east and west, maybe 2 feet apart. Each is likely 2 1/2 inches galvanized. So for example, the kitchen supply would now be a 1 inch tee off the 2 1/2 supply which returns to a 1 inch tee to a 2 1/2 inch return. No monoflow.

The original kitchen piping was a 1 inch tee off the main which was later reduced at the main to 3/4 inch copper for the 3/4 inch slant fins. I wonder what was in the kitchen originally. After all the concern over the 3/4 kitche supply and concern over pex restrictions I decided to try 1 inch pex B.

hot_rod

EdTheHeaterMan said:

In order to help you get a better understanding of how the old radiators work and how the new baseboard radiator work here is a simplified diagram of a heating system with some numbers added to visualize in your minds eye what is happening. At the bottom of the illustration there is a complete Monoflo® system. Heat circulates starting at the boiler, then it goes the the radiators then the lower temperature water returns to the boiler to be reheated.

In the upper picture in the illustration one of your radiators will take a small portion of the heated water from the main pipe and circulate into the radiator to heat the room. The pipe on the other side of the radiator will return the colder water back to the main pipe at a rate of less than 0.5 Gallons Per Minute (GPM). When someone redesigned the kitchen with a copper tube/alum fin type baseboard, they messed up the pressure drop across the supply and return pipes of that radiator. That made the amount of water going into the radiator less than the original design.

Since the new radiator requires a large flow rate (at least 1.0 to 4.0 GPM) the water took the easier path and decided not to go thru that new radiator. It is all physics and you can't break the laws of physics.

So basically, that radiator needs its own circulator pump to make it work on your system. Either design will work, home run or adding a small pump the the existing pipes. I believe the home run idea is better, but if that is not possible, then add the small pump to what you have.

It is unfortunate that you needed to learn the hard way, because this has been known by pros for over 70 years. But now you know and you can move on from there.

Good luck with your project.

Mr. Ed

I'll challenge you on that CI radiator output. Using the well know hydronic formula as seen in "Pumping Away" And the B&G System Syzer among other places

500 X flow X ∆T

500 X .5gpm X 30∆= 7500 btu/hr
500 X 4gpm X 10∆= 20,000 btu/hr

Putting that to the test for a 20 minute run time in an 8 tube column radiator bottom feed bottom supply. 1-1/4" straight through passage way at bottom.

The left hand column is less then a 1 minute run, then 10 minute middle column, and 20 minute on the right side.

It clear that the higher flow rate got hotter and got there faster.

Possibly other types of radiators behave differently? Show me some calcs or test results?

What is the measured flow rate through a radiator on a gravity system. From what I know hot water races to the highest point in a building, warms the top radiators faster, so there must be a measurable flow to the radiators? Or does it take several hours at .5 gpm to warm a cast iron radiator with gravity only propulsion?

The low mass fin tube would accelerate faster no doubt. Both would work at 4 gpm flows.

eclecticmn

Thanks again to all. I paid for some cheap monthly on-line advice place long ago and talked to one or two guys. One of them suggested adding monoflow or venturi devices which is where I got that idea from initially. Some plumber in White Bear Lake MN first mentioned adding a circulating pump and said the 3/4 inch slant fin loop diameter might be the cause. But he said he did not like doing this kind of work for some reasons he gave, compared to regular plumbing work. This after I tossed the slant fins. The previous owner sought professional device as I recall but maybe the wrong professionals.

Also, my system has a ballast(?) tank above the boiler hanging from the basement ceiling. It is a horizontal tank, maybe 10 -20 gallon or so? One pump.

WMno57

eclecticmn said:

Also, my system has a ballast(?) tank above the boiler hanging from the basement ceiling. It is a horizontal tank, maybe 10 -20 gallon or so? One pump.

That is an air over water compression tank. It is half full of air and half full of water. Its purpose is to allow the water to expand in a closed system by compressing the layer of air in the top half of the tank. Water expands when heated.
Today's hydronic systems have a bladder tank. In these, the air and water are separated by a layer of rubber. I prefer the air over water compression tank, and see no reason to change.
Your 1915 house sounds similar to my 1916 house. Over the years some of my radiators have been moved and piped with 3/4 copper. They all get hot though, and only one pump in the entire system.
Is your kitchen part of the original house, or an addition? Does your house have more radiators than it did in 1915?

eclecticmn

I have no idea how the house has changed. I think the kitchen was added. Some radiators were re-piped in copper and all work OK. The first floor bathroom has an old kitchen cupboard. My BR closet back wall looks like exterior cladding. There was a 1 inch tee off the 2 1/2 main going to the kitchen and someone reduced it to 3/4 copper for slant fins which never got warm. I am trying to get some radiators working soon but the boiler acted up.

I got Christmas cards addressed to "Grandma's house" from an older lady in California. There used to be a shed with a cow in it.

archibald tuttle

@WMno57

i'll bite. why do you prefer the air over water tank? generally more capacity was installed and available if the air charge is up or . . . ? and do they have a low petcock so you just air charge until air comes out instead of water and you know you're there? i'm hazy on how much/how quickly the air dissolves into the water and needs to be replaced as I've never managed an actual operating unit.

archibald tuttle

@eclecticmn

I still haven't seen any pictures of the (presumably) diverter tees for the radiators to confirm what the actual strategy is for balancing flow to individual radiators (or baseboard replacement loops). I noticed the debate between @Hotrod and @EdTheHeaterMan about flow speed possibly affecting whether the baseboard is (was, not that its gone) receiving flow.

how long was the baseboard loop? I don't really conceive of modest 3/4" loop although bushed down from the original as presenting so much flow restriction as to obtain no flow if the circuit was receiving flow when it presumably had a radiator piped 1" before whatever kitchen reno lead to the current circumstance.

Were your observations literally no heat in that in that baseboard loop or simply insufficient to notably warm the space but the pipes actually got hot similar to temps in main on the feed side if you recall? Is your system setup as diagrammed by @edtheheaterman with the main continuing between teed feed and return to each radiator? I think it is unlikely to be otherwise, but pictures of those tees would help those who see them regularly identify the flow diversion strategy. does one leg to the radiators have a balancing valve?

it is likely the tees aren't closely spaced enough to pump the individual copper loop although - hive mind - if the main circulator is strong enough and the loop circulator were low head modest assist could you get away with this with more widely space tees? I doubt the bushing install was so close as to remove or disturb the flow diversion of the tee installed in the main but I can't help but suspect something is up, although @EdTheHeaterMan has seen way more of this than me. I may just not have the right instinct that you ought to have been getting some flow in the baseboard–if not sufficient to provide the comfort you desire (nevermind that the cast iron retains the heat longer limiting the cycles the baseboard in the kitchen would prefer). maybe the ouijas of physics are acting up as he says, albeit normally i would expect proportional flow to the resistance, not no flow, especially with a venturi tee of some sort.

so i think your latter two pictures show you piping two rads under the window in the kitchen since you don't have one long one? and you if I understand the line on the picture, to me that the edge of the concrete looks close enough you could drill/core it from underneath at an outward angle to come up approx where the valve wants to be or at least not past the legs of the radiators into the room. It looks like you plan to use 3/4" for the run which would be easier to drill although it still goes back to whether there is problem getting flow in the loop. you could test that with a piece of pex connecting the feed and return through a loop with something teeed in the middle of the loop to let the air out (and if that something is metal or has a short metal nipple you would be able to CAREFULLY touch/hold that to ascertain if it was obtaining fluid at the temps of the main).

In the end, if you can't seem to get flow or sufficient flow from the tees and this is the only problem with the system and all other rads heat nicely, you could just run the loop back to the boiler and add a circulator for the kitchen as suggested by others. As far as the short cycling mentioned, i.e. if this zone were to call independently it would need very small part of boiler capacity and the boiler would run for short cycles and might have insufficient flow to carry the heat its making leading to higher 'bounce' and thermal stress, unless the call coincided with master house call. But there are a couple of ways to handle that, esp. if you are willing to let the kitchen ride on the general demand. I sometimes handle odd circuits like this as freewheelers without employing an XX call (end switch) call to the boiler for that zone. So I just let the kitchen thermostat call the circulator without starting the boiler so you are wasting a little electricity circulating if the boiler is cool but it won't short cycle based on small kitchen load, or wire the kitchen circulator in common with the main circulator (probably not enough additional load to overburden the relay) so it only runs when the boiler is running to satisfy the main zone.

brian

eclecticmn

Thanks for the long reply. I will carefully go back and re-read the parts carefully. The old copper slant fins are now gone (function replaced by previous owner with wood stove!) as neither I or the previous owner could get heat out of them. I recall he had a professional look at them but not all HVAC/plumbers are competent in this area. The copper pipes never got warm. Once I turned off every other radiator in the house and the copper pipe got too hot to touch.

BTW I learned here that my system is a "direct return" system.

As far as angle drilling into the concrete I decided that is beyond my skill set. I tried once to angle run a wire from basement to first floor stud wall and failed repeatedly. I did drill a single hole through the 12 inch plus basement wall once and burned out the cheap Harbor Freight rotary hammer drill. I got the single replacement under warranty.

I bought the used smaller radiators after I could not find anyone to move a single longer one. I found a longer one for free on craigslist but it would cost $500 to move it 10 miles as I recall and that was an estimate not a firm bid. I hired two movers to move the long free one but they showed up, looked at it, and turned it down. The floor needs redoing and how would I handle that with a monster radiator? Maybe in the NE US there is a larger market for such radiator work.

I will post abut the short cycling in the other topic.

eclecticmn

I can't remember the piping length from main to old kitchen baseboards. I think about 15 feet each for supply and return. All 3/4 inch copper. I removed the copper because I suspected some corrosion and maybe blockage. At the main tee I found a 1 inch nipple, 45, reducer bushing to 3/4. I wanted to valve it off so I could work on it later. I removed the bushing and installed a ball valve. I hesitated to go all the way back to the tee for fear of tempting fate as winter was coming fast. Hold that thought.

So, I add some galvanized 1 inch pipe past the ball valve so I can add pex and maybe a circulator pump if I needed it. I come down the next day and there is dripping from the tee. I must have put strain on the system and there may be a hairline crack in the nipple. Confession: I did not support the short length of new 1 inch pipe right away. Now the dripping stopped. I will replace the nipple in the summer. It may shear off so I will not tempt fate now.