Need help with hot water system

ChrisJ

I'm trying to help my brother in law and sister improve their heat.  As I have mentioned in other threads I'm getting very familiar with single pipe steam but when it comes to hot water I'm lost.



The boiler is a WM CG-4 and is rated I believe 105K BTU input.  House is 1100sqft with modern windows.  The system works poorly enough that if its 10F outside it cannot even maintain 65-68F inside running nonstop.  System is fully bled and has no air in it.  I would think 88K BTU output is plenty for a house this size especially with new windows.



He is considering replacing these rads with baseboards.  Would it improve anything?  The rads all have wooden covers with the usual decorative wood mesh / grill.  What I don't have is a good picture of the cover,  it has a mesh that covers the entire thing right to the floor which can been seen on the bottom left of the rad picture.  Perhaps this cover is stoping a draft from forming through the rad?



What should be our first step?  I was planning on starting with a thermometer to measure the outlet and return temps at the boiler.

Ironman

The Covers...

Are most likely your main problem. Those are convectors and there must be a cover that is solid in the middle where the element is, and slotted or open at the top and bottom. Putting a grille like they have on it will greatly hinder the convection of air.



Try blocking the cover with sheet metal at least 12" high, all the way across the width of the element. Place the bottom of the sheet metal even with the bottom of the element.

ChrisJ

Ok

Here are detailed pictures of the covers.

I will have him try the sheet metal trick.



Thanks for the help!

icesailor

Hot Water Radiation:

First of all, those are not "radiators", they are "Convectors". They came from the factory with metal covers, NOT wooden ones. The metal covers are designed as part of a UNIT that will have a listed and rated OUTPUT. If someone decides to redesign the units with wooden covers, they probably cut the output down considerably. The elements with the fins in them must be clean and free of dust and animal hair. There must be a free flow of air through the elements and the cover in front must be tight to the element to force the air through the element. The openings in the top of the grill are designed to keep the air flow high and unrestricted.

Here is a third world way to check this. Get a couple of cheap cooking/candy thermometers from your favorite cheap store. Put one on the supply and one on the return of the boiler and wrap it with towels or insulation. Wrap it so you will be able to see the readings. Look at what the high limit is set at. If it is 180 degrees, take note. Start the system. Watch the temperature going out and coming back. You should mostly have a 20 degree difference in what is going out into the system and what is coming back. If the boiler goes to 180 degrees and the burner stops but the circulator doesn't stop, and the rooms are cooler than the thermostat, and it is only 40 degrees outside, you do not have enough heat going into the rooms because of the screwed up heat emitters.

When the system was running in the cold and it wouldn't get hot, was the burner cycling on and off? If so, it is the radiation, not the boiler.

You need to fix the convectors to get them to work properly.

ChrisJ

Ok

I assume this is what the cover should look like.  Can these be bought or will they have to be made?



I'm guessing with the wood grate over the convector it simply sits there stewing in stagnant air rather than convecting....

Ironman

That's what it should be

I don't know if they can be puchased separately.



Try: Becon Morris, Governale or First Co. for starters. I'm sure they're others.

icesailor

Covers:

There is a major part of your problem. The air is restricted at the bottom. They are usually cut away at the bottom allowing a free flow of air through the unit. Then, there is an amount of radiation of the metal getting hot and radiating out into the room. The free flow of air is important because as the cooler air enters the fin space and the heat is given off, the air expands and accelerates. Making more air come out than goes in if you understand what I mean. The metal cover must be in close contact in the front so as not allow the air to go AROUND the element but THROUGH the element.

I've seen a lot of creative carpenters make beautiful cabinets around radiators and completely screw up the heat emitting value of the emitter. Because they didn't understand how they work and the owner wants them covered.

Measure the height from floor to the top of the cabinet, the distance from left to right and the distance from the back of the metal cabinet and the front of the element for all the convector cabinets. We can tell you how much they are supposed to be putting out by design. I'm quite sure that there is more than enough radiation in the house to keep it warm.

icesailor

Covers:

Don't bother looking for covers. I've only seen a few of those types around. That company is long out of business or changed the design. They also had a flat front cover that didn't go to the top and had a stamped. louvered grill that the cover hooked on.  Most today have rounded front covers at the top. Very few have the straight top like you have. If you had the "normal" type, it would have been a difficult carpenter project to make them nice looking.

I suggest cutting out the bottom like the one in the picture. Those are nice covers. If skilled, you could radius the bottoms like what is in the picture. The sheet metal inside is a really great idea. Bring it down to the bottom of the element or just below it and bring it up to a place that is high up on the grill. If there is a space of more than 1/4" between the metal on the grill and the element, make a wooden filler strip and cover the wood with true aluminum duct tape. NOT the cloth type.

Go for it. You will be amazed at how much better they will work.

Sensi Jimmy

recessed convectors

this was a great idea  lets recess the convector in the outside wall to heat the indoors,  on those really cold days this type of system just doesn't seem to produce real good heat output.

billtwocase

I've never

had a complaint about insufficient heat with wall convectors, unless they were plugged with lint/dust, or the louver door was closed over the top of the fins. Some were even cast convectors. They work great if they can breathe

icesailor

Hot convecters

Absolutely correct.

They work fine. I never saw an old house with them that didn't heat properly. The old dead guys usually over radiated the rooms anyway.

Mark Eatherton

Field Sperimentation...

With a decent exposure to outside cold weather, check the differential in temperature between the supply and return. If the "system" is not delivering welll through the convectors, the DT will be short.



Now, take some aluminum foil and "simulate" a good cover with plenty of inlet and outlet air (~3") and see what effect it has on DT. If DT increases, you are headed in the right direction. Now, you can find a good sheet metal fab shop to build you some good and functional covers. Basically, due to the poor design of the current covers, you are quashing the majority of the convectors output. (Like 60%...)



Follow what Ice said about swoopy curvy air guides and tight clearance tolerances for maximum performance of the convection elements. That particular convector is very dependent upon the "chimney" effect, and if it is missing, then output suffers significantly. You have little to no chimney effect occurring due to modified covers.



Let us know how your experiment went.



BTW, simple back of the PC math tells me your heating system boiler is about 2 to 4 times bigger than normal. Shouldn't be a heat availability thing... Could be a flow issue (dead pump) and if so, you will experience a BIG delta T.



ME

ChrisJ

thanks

for all of the info.  I would've never figured out what these were without your help.



My brother in law is going to try and make something up using aluminum inside the wood covers.  He is also going to cut out sections to let them breath better via the top and bottom.

I believe he is planning on removing them next spring and installing baseboards in their place.  He hates the cold draft he feels blowing through them when the heat is off and would rather insulate the wall and sheetrock over the spaces.