Putting the Rad in Radiator

My grandmother had a tea cozy. Woven from wool of subdued colors (probably the only wools available), her tea stayed warm all afternoon because (wait for it…) the cozy kept the heat inside the pot!

In overheated New York City apartments, it would be great to be able to keep some heat inside steam radiators. Of course the super has to turn the heat up enough to quiet the noisier tenants in colder apartments. But once he does, most of the other apartments in the building are overheated, and “double-hung thermostats,” aka windows, are regulating temperatures by exchanging cold air for heat and wasting lots and lots of fuel. What to do?

One answer is thermostatically controlled radiator valves (TRVs). These keep the steam out of the radiator unless they sense a room temperature below an adjustable set point. They work well on hot water and two-pipe steam systems, and they’re OK on one-pipe steam if the super knows enough to keep the system steam pressure down. BUT they require plumbing work to install, the resident has to let the owner in to install the system, and given the hassle, the owner may prefer to let the residents stew in the steam. (There are owners who do not seem to be tempted by devices that pay for themselves in fuel savings in a few years – surprising numbers of them.) What can a tenant sweltering in an overheated apartment do?

Soon, urban winter heat-stroke victims, you may have an option that does not depend on the cooperation of the building owner! A New York City startup with a big idea is coming to your rescue with the radiator cozy, a device that will imprison the heat in your radiator, only releasing the modest amount needed to maintain the temperature you choose to set1. With your mobile phone!

Any technology that puts decision-making power on a comfort-inducing item completely in the hands of tenants is a game changer. If you’re overheated, you don’t have to even talk to the owner to install a radiator cozy, and in NYC rental world, that’s often a plus. But if you did, it’s hard to see what an objection could be, since you’ll be lowering demand for fuel.  In fact, owners who are reluctant to bring in the professionals needed to install TRVs should consider paying for cozies themselves. At $300 each, a five-year payback2 seems easy to come by if the cozies are installed in overheated rooms with windows that are often open.

Disclaimer: Urban Green Council does not endorse companies or products, and since this product is not yet available, it would make no sense to do so even if we did. But we totally endorse the idea of better tenant control of heating systems, so please consider this a “heads up” to potential progress in this area.

My only complaint is that the developers felt they had to bad-mouth TRVs in some of their material. Since I live in an apartment that is made totally comfortable by TRVs, and has been for years, I found that set of complaints unconvincing. And they don’t need them: the cozy’s ease of installation is a very big deal. Nana would have liked it.

Note 1: The technical stuff: The cozy is an insulated box that covers the whole radiator. It has a fan that comes on when the room temperature drops below the set point, blowing air through the radiator and out, bring heat to the room. When the room warms up, the fan shuts off. Maybe it could be simpler, but I don’t see how.

Note 2: If a radiator services 300 square feet, and an NYC building uses 15 Btu/ft2-HDD, lowering demand by 10% will save 2.2 million Btu of fuel, worth about $65 at $4.00 per gallon.  That’s less than a five-year payback. But will it save 10%? The developer says “up to 30%,” but we all know what “up to” means. If they are only installed in overheated rooms with presently open windows, I think 10% (for that radiator, not the system) is a pretty sure bet.

About the authors

Richard Leigh
Richard Leigh is a Visiting Professor of Physics at Pratt Institute, primarily teaching courses in building science. He formerly served as Urban Green's Director of Research, where he managed research projects including the 2016 New York City Auditing and Benchmarking Report for 2013 data and 90 by 50, showing that New York City can reduce its greenhouse gas emissions 90 percent below current levels by 2050.