Hydro-Air versus Cast Iron Baseboards

10 years ago

I am gutting the 2nd floor of my 1960 home outside of Boston which has been in my family since 1961. Currently the house is a ranch with two small rooms on the 2nd floor that mostly occupy shed dormers facing out the back of the house. They are heated with cast iron baseboards on one zone of a monoflo system (matching the rest of the house; 4 zones total)

The renovation includes adding three dormers to the front of the house to recapture some of that useless knee wall space and essentially turn two rooms into four.

We love our baseboards and the plan had been to reconfigure the existing ones and use some leftovers from first floor renovations to add identical baseboard to the new rooms.

The HVAC contractor has raised three concerns. (1) that we may not have enough baseboard in hand to complete the job (additional concerns that disassembly/reassembly may cause the press fit of the different sections to leak). (2) since the heat had always been on the back walls of the 2nd floor, running piping from radiators for the new front dormer rooms to the heating loop in the basement would require creating new pathways through the walls and may be somewhat destructive and prohibitive. And (3) that given the uneven sizes of the rooms, the natural baseboard placement will give very uneven heating when certain rooms end of with significantly greater length of baseboard.

The HVAC contractor's solution is to scrap the baseboards and go with a hydro-air system since we are planning to install A/C ducting anyway.

I have very much enjoyed my radiators and haven't loved older forced hot air systems of other homes I've had experience with (just don't like air blowing on me and have always thought it creates dust, etc). As we'd been planning this for months, and the renovation is underway, I feel this is coming at the 11th hour and I'm looking down the barrel of a choice I don't want to make.

Has anyone had experience weighing one type of system against the other. Mostly I'm balking because (1) I feel like this choice is outside of my control and (2) I've had a functioning system of a type that I like and that has served my family well for 50 years and I have exactly zero experience with the alternative.

Are there other concerns I haven't thought or or am I making a bigger deal out of this than necessary?

Thanks.

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Comments (5)

jackfre
10 years ago
I think I would try to salvage what I could of the hot water baseboard system and go with mini-splits for the rest of the house. By adding the mini-splits you can heat very effectively with them as well as being able to get your cooling and dehu.

It is extremely difficullt to add ductwork to a home. You loose space. As well, the mini-splits are individually zoned and significantly more efficient. Fujitsu and Mitusbishi are the two biggest brands in your area. Where are you "outside of Boston"?
ben.fachner
Original Author
10 years ago
Thanks for the feedback. The house actually had existing A/C ducting running down the small attic space in the ridge of the roof. The ducting needs to be augmented for the new rooms, but seems all the rooms could be heated/cooled from above without losing any usable room space to install ducting.

The house is in the Weston/Wayland area.

I'm not all that familiar with mini-splits, although I've seen the them used for A/C in other countries. I'll try to read up on them.
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I have a old home built around 1900, give or take a few years. I have a hot water heating system. Mine has the old steam Rads but were converted to hot water by changing the valves, and bleeders long before I owned it. you need to know what type of system yours is, hot water or steam? steam systems can be a one or two pipe system. hot water is two pipes. the two pipe steam and hot water systems use one to send out hot water or steam to the rads or baseboars and one for return. One pipe steam uses the same pipe to send the steam to the rads or baseboars then when it cools and condenses back to water it runs back to the boiler via the same pipe to be reheated. the two pipe is more efficent and if the system is steam you can convert to hot water with out major replumbing since it has a return. I have been told that hot water systems are less costly to run since you are only heating the water to 150 or 160 vs. 212 to create the steam. also check to see what kind of boiler you have and how the water is delivered. If there is a circulator thats a good sign the boiler is not super old like mine was when I bought my house. no curculator pump means its gravity system that relies on the heated water to rise natrually and fall back by the returns. I changed out my boiler last summer to a new forced hot water system, it heats the rooms much more evenly than before. the trouble spots for me were the radator valves, some of mine leaked when I refilled my system. I was able to tighten up the packing nuts and stop the leaks. my old system had a manual fill and the valve was stuck shut so I could not add water to completely fill the rads on my 3rd floor. That is now not a problem with the new boilers auto fill. If you have Rads you should purge air from the bleader valves at the begining of the heating season. you may not have any air in them but any air trapped in the rads will effect the heat output. check out Burnham's web site they make and sell boilers rads and baseboard for hydronic heating systems. that my help you inedtify what is in you home. Here is a link that might be useful: Burnham
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Hi. I am assuming that you have a boiler, not just a domestic water heater. I would definitely separate the upstairs from the downstairs. One main reason is the upstairs usually gets more sun and requires less heat than the downstairs. If you have the option, why not zone the upstairs bedrooms separately? It sounds like the baseboard on your added bedroom upstairs was installed at the end of the hydronic zone loop. If the piping was undersized, or the pump not large enough, and the other radiators were on, there may not be much heat left in the piping to support another baseboard or cast iron radiator. One way to check is to turn off the flow to the cast iron radiators (usually via a gate valve on the radiator supply or return piping) and see if the other baseboard gets hot. If it does not, it may be air locked and need to be purged. It it does get hot, consider isolating the room as another zone. The current piping is insufficient to provide the needed btu's to the baseboard. Also, on your boiler you should be running at around 180 degrees if possible (assuming it is not steam). If you had a slab system, you would not want to exceed 140 degrees. You might want to have a service man come and check the temperature split between the supply and return lines at the boiler. You may also have a balancing issue, depending on how the header was piped.
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fsq4cw
10 years ago
I would agree with Jackfre. ThatÃ¢ÂÂs good advice. My experience with home like yours has been keeping the hydronic system and integrating it into a geothermal, all hydronic heating and cooling system without ducts. Those that have done it are very happy with the results, although it is expensive.

From a technical point of view your contractor may not have given you bad advice either but it seems your preference is for hydronic baseboard radiant. You could heat the newly renovated area with hydronic in-floor radiant as well. One question for your HVAC guy is what water temperature will you need with what heÃ¢ÂÂs proposing. The higher the temperature the more energy youÃ¢ÂÂll consume. Few options will require a lower water temperature than your cast iron rads but in-floor radiant could be one of them depending on spacing between pipes.

What source of energy are you now using for your boiler, how old is it, what size and efficiency is it?

SR
ben.fachner
Original Author
10 years ago
The boiler is a Viessmann natural gas boiler. A Vitodens 200 W, and the EnergyGuide sticker on it pegs efficiency at 96.1, with I think BTU output of 127,000. It was installed approximately 4 years ago.

It is good to hear I'm not out in left field wanting to keep the rads. I guess at this point it is just a matter of do I want to deal with tearing up the 1st floor to get the rads' input/output piping to the basement and possible expense if I need to buy significant additional length of baseboards.

I will definitely ask about the water temp for the hydro-air system. Is there a rule of thumb for what the rads require?
fsq4cw
10 years ago
Excellent boiler! Mess should be minimal to install piping for a hydronic system. You may be able to find a local source of reclaimed/reconditioned rads similar to or exactly as you have now at a reasonable price.

Btu output of any rad will depend on water temperature and flow rate. You will have to consult with the supplier for a chart of Btu output verses water temperature for a given length of rad at given flow rate etc.

Since you are renovating, you have the opportunity review the configuration of your piping (primary, secondary loops, reverse return, zoning, etc.) as well as Ã¢ÂÂOutdoor ResetÃ¢ÂÂ, variable speed pump(s), zone valves, thermostatic temperature controls at the rads, automatic air & dirt elimination, water chemistry, etc.

Modern hydronic systems today are VERY efficient - and NOT your parentÃ¢ÂÂs hydronic system of the 60Ã¢ÂÂs! Remember, per given volume, water is 3,500 TIMES more efficient than air at transferring (moving) heat! The Hydro-Air system will also require a large blower fan motor whereas an all hydronic system only requires a very small, quiet circulator because of the efficiency of water as a transfer medium.

This is your opportunity to Ã¢ÂÂGet It RightÃ¢ÂÂ - take the time, as the energy savings and comfort factor can be huge!

Think Water!

SR

Here is a link that might be useful: Steam Experts

Hydro-Air versus Cast Iron Baseboards

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