TRV's and mixed emitters.

mars_6

Hello wallys, I have a project that is a remodel that I am currently in the design phase of. It is a 1922 build in Denver that has CI rads, the home owner whom is a good builder for my company wants to replace some of the CI rads with baseboard heaters. I will be using a TT 60 boiler as that is what he manual J indicates I want to use. I was thinking I may want to go ODR controlled by a thermostat with TRV's at the individual heat emiters to maximize the efficiency of the boiler. my question is if I have some base board rads and some CI rads would this be a good mix? Or would I be looking at finding unintended consequences. Thanks for any and all responses. Mars

SWEI

The most important thing is to size the new emitters for the same water temp the old ones need. Room by room heat loss, then look at the derating tables for both. If this were my customer, I'd be suggesting a low profile radiator type design rather than convectors. Runtal UF comes in 6", 9" and 12", Myson Select in 12", either will outperform convectors at low temps, and they both look a lot nicer in my book as well. The bottom of your reset curve will be a lot lower and a much better match for those old cast iron beauties.

Eric_32

I have never seen a house where cast iron emitters and copper fin baseboard were on the same zone and they worked happy together.

If you do it, put them on a different zone, or replace the cast radiators with cast iron baseboard like Burnham 9A. Harmony....

I have gone to so many jobs and have seen it, asked the customers how the system works and they all say the baseboard doesn't put out enough heat, the room is always cold, because it cools off too quick, or it gets air bound easily because it's being bled using a coin vent and piped off the same monoflow tees the cast iron was, and the installer pipes it like a loop system going up and down and back up in the basement creating a trap for air.

Now I don't know how the TRVs will effect this, maybe it will help, maybe not.

My .02

SWEI

TRV's will help with balance, but they will not fix the problem of fall-off at lower temps on the baseboard. This will force you to raise the lower end of the reset curve, which will cause overheating in the rooms with CI rads (unless you put TRVs on all of those, or groups of them, or pipe the baseboard on a separate zone.) It's far better to just select and size the new emitters properly.

mars_6

Thanks for the info gentleman, I have had the chance to walk the project today and have a count of the Peerless radiators I have to work with. I will try to convince my contractor to keep the radiators on the main floor, run the supply and return piping so each radiator is supplied and returned directly off of the Alpha pump that supports the zone and Install TRV's to control individual radiator temps. If he will ceded me with the wall space for this I think I can provide him with the type of system that will be true to the house yet also modernized to the 21th century.

SWEI

IMO properly sized short panel rads could do that.

Best of luck with the project.