Reducing water flow in upstairs baseboard convectors

Plumdog_2

Comfort-Trol zone valves. I believe they would be normally open and power closed. They are a heat-motor type. Also very cute.

AMGeek02476

Reducing water flow in upstairs baseboard convectors

~50 year-old Cape Cod style (1-1/2 story) house. Living area ~1350 sq. ft. Forced hot water heat using
baseboard convectors. Single zone. "Monoflow" configuration. All convectors are tributaries off main loop, which runs around the periphery of the basement just below the ceiling. Each convector is connected to the
main loop via a Venturi T (on the downstream side) and a conventional T (on the upstream side). There are
no shut-off valves for any convector.

New oil-fired Weil-McLane burner/boiler installed by oil dealer 11 months ago. Works "too well" and that's the problem: Especially in very cold weather (zero degrees F, for example), if the thermostat, which is, of course, on the first floor, is set for 67F, temp throughout the first floor will be very close to 67F BUT temp in upstairs bedrooms will be in the mid 80s. With the original system, this was not as serious a problem because the pressure of the heating water was lower. In fact, toward the end of the system life the pressure dropped so low that one of the upstairs convectors became air-bound. I've talked to the oil dealer about lowering the pressure but he says this can't be done.

Several plumbers have recommended a true second zone with an additional circulator pump. The extent of the
project--more than the estimated $5000 cost--scares me, however. I envision the project causing more problems than it will solve. Would it work to have a plumber install manual valves in the two bedroom tributary loops--in the basement on the tributary side of the Venturi T's? If these were multi-turn valves, I think I could reduce the water flow in the two affected convectors so that the upstairs
temperature would remain comfortable under a wide range of weather conditions. I think that, at worst, I might have to adjust the valves a few times each winter.

Aside for the need for experimentation to obtain reasonable valve settings, do you see any problems with this approach? If so, please explain. Thank you.

Brad White_185

Some thoughts....

Given that you have convectors, may I assume that the connections are reasonably accessible to each element? Why not install thermostatic radiator valves (TRV's) at each, or at the very least, those that tend to overheat? This way your control is temperature-based.

I will opine here that perhaps you have insulated your attic or that this was done since the house was constructed? Thus perhaps it is that your emitters (convectors) are now over-sized whereas before they were adequate?

All things being equal, flow does not equal heat output.

(Flow is a very forgiving variable- cut it in half and you still get about 90% of your output. Quadruple your flow and you will get maybe another 10 percent output, you see.)

Bottom line though is that you could install TRV's on at least the upstairs radiators, as "high limit" devices which respond to comfort not arbitrary restriction.

By the way, the system pressure really has nothing to do with heating output, save for the drop in water level below the upper floor. A house your size would need to be at most 12 to 15 PSI (12 really should be enough when cold) and with 4 to 5 PSI at the highest radiator. That is it.

kevink1955

If by convectors you mean steel enclosed with a fined element about 6 inches deep you could just cover some of the element.

I have 1 small room that has a radiator that is 3 times to large for the room. I cut a length of sheetrock to cover about 5/8ths of the element and the problem was solved. I now have a 4 foot radiator that works as a 1 1/2 foot. Works for me.

AMGeek02476

Reducing water flow in upstairs convectors

One plumber did mention adding a thermostatic valve at one end of each convector. The problem with that idea is that it would be difficult to make enough room for a plumber to work in the rooms with the overheating problem. I was really hoping for an approach that could be implemented entirely--or almost entirely--in the basement.

My original idea was to insert a solenoid valve (rather than a manual valve) in the basement in series with each of the two offending convectors--that is, within the two tributary loops for the upstairs bedrooms. These two solenoid valves would be controlled by a single (new) upstairs thermostat; they would operate simultaneously and would completely shut off the water flow in the two upstairs-bedroom convectors except when the temperature at the new thermostat was below the set-point AND the single existing circulator pump was operating. There IS room to install a thermostat in the short corridor between the two upstairs bedrooms.

I referred to this approach as a "poor man's second zone" or a "fake second zone." There would be no separate circulator pump for the upstairs bedrooms and hot water would be delivered to the convectors in the upstairs bedrooms only when the single existing circulator pump was operating. I do not view it as a problem to be unable to raise the upstairs temperature without raising the temperature on the first floor. I can't do that now! Nor do I consider it a problem to occasionally have to change the settings on both thermostats to increase the temperature in the upstairs bedrooms. But I can't convince the plumbers that I have spoken with that this "fake zone" idea is any good; they want nothing to do with it! I still believe it would work well.

In fact, from what I have read in the last day or so, the idea of having a "zone" that shares a circulator pump with another zone is not unique to me. Although it is not a common arrangement, it apparently IS sometimes done. So how do I find a qualified plumber who would install such a setup (and not tell me I am crazy or asking for trouble)?

TGO_54

One potential problem

is pipes freezing from lack of flow. If your new thermostat in the center hall is satisfied for a few hours on a cold windy day, you may find out the hard way that a heating pipe is un-insulated and near an exterior wall.

Using TRV's on each convector would decrease the possibility of this, they limit flow and are less likely to be fully closed during very cold weather.

Have you considered adding outdoor re-set to the system?

As to finding someone to do the job, go to the header at the top of the page, click on resources, and then find a pro.

Let us know how you make out.

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

AMGeek02476

Re: One potential problem

Thank you for your help! Believe me, I DID think about this. It scares me more than just about anything else related to this project. Although my two previous postings didn't describe this feature of my original idea (with the two solenoid valves), I had concluded that the valves selected should be normally open to fluid flow. That is, if the coils are not energized, the valves should allow water to flow in the convectors as if no solenoid valves were present. Only if the temperature in the hallway between the upstairs bedrooms (where the new thermostat would be located) rose above the setpoint AND the power was on in the house (that is, a winter storm had not caused a power outage) could the solenoid valves shut off the water flow in the upstairs-bedroom convectors (and thus limit the temperature in the bedrooms). Also, if there was a major winter-storm emergency that knocked out the ac power and made it necessary to temporarily abandon the house, the normally open valves should make it possible to drain the system in the same manner that it can be drained now.

I have lived in the house for 44 years and so far, I have not faced such an emergency, even during the notorious Blizzard of '78. I pray that I never will! However, as far as I can tell, there is no such thing as a zone valve that is normally open to fluid flow. That would mean selecting as zone valves devices that were not expressly designed for my application. Please comment if you can.

zeke

Your idea is fine. I especially like the normally open feature which allows shutoff of the solenoid only on vertemperature.And the implementation should be simple. Get a thermostat with "cooling" capability and use it in the "cooling" mode only . Then when the temp goes above your setpoint you use it energize the standard zone valve.

Just hire a plumber to do it as you designed.

zeke

Your idea is fine. I especially like the normally open feature which allows shutoff of the solenoid only on overtemperature.And the implementation should be simple. Get a thermostat with "cooling" capability and use it in the "cooling" mode only . Then when the temp goes above your setpoint you use it to energize the zone valve. If you can't get a NO ( normally open) zone valve then use a NO solenoid valve or an industrial on/off NO valve to do the job.

Just hire a plumber to do it as you designed.

Tom Hopkins

I am faced with a similar problem. I need to install 4 radiators to the Monoflow system. The room where radiators are to be installed are better insulated than the rest of the house. Can you tell me which options you have decided on?
1. multi-turn valves in the basement?
2. TRVs
3. poor man's second zone

Thank you, Alex

Roland_15

Overheating

Hi AMGeek,
I have a similar issue with my Cape. I asked a heating contractor about adding a zone due to the upper floors getting too hot when the heat is on. He told me to keep the doors to the upstairs rooms closed as the heat is rising and pooling in these rooms.

Also per Kevins' suggestion, cover part of the convector elememt. I used aluminum coated bubble wrap as I had lots of it on hand. You can probably get it for free at a pharmacy as it's used to ship perishable drugs.

You don't really want to reduce flow in the system you described. I have exactly the same arangement as you and also considered a solenoid which would bypass flow to selected convectors without disturbing flow to the rest of the system. The possibility of frozen pipes convinced me not to do it.

Good Luck, Roland

I found the cheap way out is really very satisfactory.

m dewolfe

too much heat

Lets step back and take a closer look at the problem. The way I see it you had no problems with the heat until your oil company changed out your boiler, now you have too much heat/uncontrolable heat.....hmmmm...somthing changed.. could be a phantom flow problem or somthing plumbed wrong. I would take a closer look at your install. Get your installing contractor to come back and make it right!