any way to enhance baseboard output?

R. Kalia

We have a couple of rooms that have cast-iron baseboard. These rooms stay cooler than other rooms. There is no perimeter space for more baseboard. We could replace them with radiators, but before going that route, I was wondering if there is a way to 'turbocharge' baseboard. For example, a long thin blower under the baseboard would probably suck a lot of heat out...is such a thing made and is it worthwhile? Any other ideas? Many thanks!

Nick W

You could stack another row on top of the existing. Two-tier baseboard is a rare but functional option when wall space is limited.

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Unknown

Yes , we saw that

in the Poconos a few weeks back , in a restaurant . Cast iron baseboard with another row of it on top , painted to match the wall trim . Looked fantastic .

How is your cast iron baseboard piped , R. ?

Ted_9

What about raising the temp of the boiler slightly. 185 to 190 degrees. It may put out some more btus.

Please hire a professional to do this.

JimGPE_5

Don't

Some things that won't help:

Increasing the hot water flow won't help.
Increasing the airflow will help, but it might be ugly and noisy.
Increasing the water temperature will help. Your improved heat transfer will be approximately given by:

(New water temp - 70)/(Old water temp - 70).

Bumping the water temp from 150 to 170 would give you a 25% bump in capacity. But do hire a pro to do this for you.

Also, raising the loop temp will affect the other zones/rooms the same mount, and the thermostat may be satisfied earlier, shutting the boiler off earlier, meaning that you did not cure your problem. You need to raise the water temperature in this room only, which may not be easy.

R. Kalia

exactly

> Also, raising the loop temp will affect

> the other zones/rooms the same mount, and the

> thermostat may be satisfied earlier...


Exactly. Having a different water temp just for these two rooms is not cost-effective.

R. Kalia

piping

> How is your cast iron baseboard piped , R. ?


I hope I have understood your question...in one case there is 3/4" copper pipe to and from the boiler. Pipes come through crawlspace and go up into kitchen. In the other case it is cast iron pipe and the baseboard is in series with a radiator. Does that answer the question? Why did you ask?

Two levels of baseboard is something I hadn't thought about; it should help, except I assume it doesn't quite double the BTU output since the upper baseboard is seeing some warm air coming into it from the lower baseboard.

All other ideas gratefully received.

Ted_9

Can this room be zoned? Bring a supply and return to the boiler and runit on its own zone?

Please to note: Pex tubing can do some wonderful things .

R. Kalia

yes/no

In one case, yes. In another case, possible but not at all easy. Everything is a matter of cost vs benefit, of course. But you are right, zoning would let the water run longer and thus make up for the lower output.

flange

you say that some rooms have cast iron baseboard, what do the other rooms have. if the answer is fin tube, therein lies the problem. cast iron needs long run times, as it warms up slowly then cools down slowly. fintube heats up quick then cools down quick. if the thermostat is in the fintube area the cast will never get hot enough. if there is some other heat source in the other rooms, please describe here....................

Unknown

That's the answer...

Baseboard and radiators mixed together on the same water temperature doesn't work well.

The radiators will contain so much iron and water that they take a long time to heat up and to cool off. The run times and off times will be longer than a baseboard zone would. Especially the off times, while all that warm iron and water gives up it's heat.

The other factor is that the radiators are SOoooo oversized, due to the engineering thoughts of the day (which we are now re-learning), that the thermostat satisfies when the boiler water is only around 100-120 degrees F. Baseboard usually ISN'T oversized, and get's figured for a supply temperature of 180° F.

It never sees water that is that hot, connected to a radiator zone, so it never reaches it's rated output. The baseboard is never allowed to reach it's rating.

If you have a "one temperature boiler", you need a system that can all run at the same temperature.

Turning the boiler water temperature up simply won't help. The thermostat controls the water temperature, by stopping the system when the room get's warm. If you want to see 180° F. water temp, you'll need to turn the thermostat all the way up and run the boiler untill ALL the water reaches 180° F, and ignore what the room temperatures do. See how the aquastat isn't controlling the water temperature; the water in the system actually is? The temperature control is only a limit. Compare it to a bicycle going up hill, with a brake on it that locks up if you hit 180 MPH. The limit isn't a factor, the load (the hill) is. The water volume in your system controls the temperature. The rooms with radiators and lots of water will have heat faster and longer than rooms with baseboard, on a mixed system.

That's the nature of them.

Noel

R. Kalia

should have made this clear

> you say that some rooms have cast iron baseboard,

> what do the other rooms have.


Cast iron radiators. Sorry I left that out.

R. Kalia

yes...

This is exactly my situation, and I am trying to reduce the problem by increasing the baseboard output. There is not a huge difference now, perhaps due to exchange of air between the rooms, but there is a difference.

Boilerpro_3

Getting a mixed system to work

Besides the sizing limitations that Noel spoke of, there is a way to get low mass heating units (fin baseboard) and rads to work well together. This is to run the circulating pump continuously in order to move the heat stored in those big rads through the system and back into the fintube baseboards. The thermostat then only controls the heat source, usually the burner on the boiler.

For those wetheads out there, the rads act as buffer tanks and store heat, which needs to be moved into the whole system to keep the heating even.

I have done this many time quite successfully.

Boilerpro

R. Kalia

this is exactly my plan

Constant circulation with cooler water (i.e. outdoor reset) is precisely what we want to do next. The reason I posted the question about boosting the baseboards is to try to get ideas about reducing the problem (which is difference in temp between baseboard rooms and radiator rooms) rather than have it get worse when we go to constant circ.

You seem to be saying that the current difference in room temps will be reduced when we go to continuous circulation. Is this completely obvious?

It seems to me that with lower temp water, the baseboards may emit even less than the radiators (because of their nonlinearity) so the difference could be made worse. On the other hand you are right that currently the radiators "store" more heat during periods when the thermostat (and thus the circulator) is off. I am not sure where all this will balance out, and I don't want to find out next December when we really need the system to work well!

Boilerpro_3

Constant Circ

I have found this always improves heating balance.

In addition, if the home has almost all heavy cast iron radiators, especially the old column style that hold lots of water, the boiler is properly sized to the heat load, and the system is one zone, outdoor reset really does little to improve comfort. This is because the system water temp changes very slowly during each on cycle and the themostat is satisfied before the system ever changes temperature much. th huge mass of the system acts like a giant thermal flywheeel. I have found that on a typical winter day that a converted gravity system (large pipe, large rads) will only change about 20F from the beginning of the 20 minute long firing cycle to the end. This corresponds to the typical differential of many reset controls.

Just let the pump run all the time, and fire the boiler with the thermostat, with a proper anticipator cycles per hour setting (I prefer Honeywell electronic stats for this type of application).

Boilerpro

Uni R

How is your house piped?

Is it possible to supply these baseboards sooner than the other emmitters on the same circuit? I.E. Have them closer to supply temp than return temp.


Also, is there any way heat loss for these rooms can be better controlled?

Unknown

I'm with him

I've also done this. There isn't any off time, so the storage factor goes away. There isn't really much variation in the water temperature, either, and this is also good.

You're right, though. If the installer just guessed at how much radiation belongs in those rooms, you'll find out soon how well he guessed.

Noel

Lee_5

Increase the insulation ?


Can you reduce the rooms heat loss by window improvement, wall, floor, ceiling insulation ?

Mark J Strawcutter

trvs

If he ends up with gross imbalance between rooms, then TRVs would be a logical next step. And with TRVs outdoor reset becomes worth considering.

Mark

Reynz_2

Constant circ

I have been through a three month process to do almost the same thing you are doing. I have learned, with much discussion that constant circulation is absolutely the only way to do it. My house, upstairs and down is much more comfortable. Your only difficulty is radiator vs. cast iron baseboard. I have cast iron baseboards. They are about 550 BTUs per foot at 180 degrees. I'm sure, with its mass that the radiator puts out more heat then the baseboard. Hummm, everyone had talked to me about TRVs, non-electrical, hooked up to the radiators, however, they would not fit on my baseboard rads. They allow the radiator to be turned off when a certain temp in the room is reached and allow the baseboard rads to keep chugging along. They would however, only fit on the larger radiators. It seems that with too much heat in some rooms and not enough in others, TRVs would be the ideal fix for you. I am not an HVAC pro, just a homeowner.

Also, I have one room, at the end of a long baseboard run, from a small room, through a hallway and into a larger room, that eventually doesn't get enough heat (the largest room) because it is at the end of this run. The two-tiered baseboard suggestion is very interesting. In theory, it should at least give me 1/2 more BTUs as the single CI Baseboard in the room, right? What do you think?

ScottMP

I would

start with making it a seperate zone, before you try any control stratigies.

Most important is a heat loss for the room. Is it undersized ? Or is it just not having a long enough run time ?

Due the math first and if its sized correctly then go for the seperate zone. Thats the Whole idea of zoning ... comfort.

Scott

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jw

Put a box on it

Seriously! Try to REDUCE the overheating rooms by impeding the flow of air over the rads. You could try this easily with some cardboard and duct tape as a trial measure to see how much cover you need.

DIY Homeowner

How about.....

If a separate zone is not possible, is it possible to change the order of the radiators on the existing zone? If it is, you might try piping it so that your cast iron radiators are the first radiators on the loop, with all your fin-tube after the cast iron.

Bob Gagnon plumbing and heating

john wood

is right. instead of increasing the baseboard in your cold rooms try cutting down on the output in your warm rooms. this will keep your circ. pump running longer and the cold rooms will be warmer. i use tinfoil over some of the elements to cut down on convection. bob

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