Radiators and fresh air/AC
We have a wonderful 1913 home that we are going to be doing a deep energy retrofit on. We really love the hot water radiators for heating. For their traditional look and great warmth. We will be installing a fresh air system and AC. We realize that any AC system we install will also have the capability to heat also. Are we crazy for keeping the radiators? We realize that with the much improved thermal performance of the house we will not need as much heat as the radiators produced so had been thinking of running reduced water temp through them.
Are we clinging to something that is just a relic and should be removed? Either we just haven’t searched well enough but the predominate articles / responses we see are to not have both systems IE get rid of radiators.
We are in Wenatchee Washington so 5b.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
If you like them, keep them! You have options here:
An air-to-water heat pump would heat with the existing radiators and cool with the new ductwork.
Or you could install an air-to-air heat pump that heats and cools with the new ductwork, saving the radiators for when it’s coldest.
It’s extremely easy to lower water temps and cut the output. You can adjust the temps based on outdoor temp and even add TRVs, which control temperatures room by room.
Good to hear my thinking from research and want is not false. I had also thought of using an air to water heat pump like you suggested with low water temp distribution to radiators. The radiators would then run on a pump circulation system versus rising heat circulation of the old system. I have found the SpacePak air to water units. What are thoughts on their Small duct High velocity cooling system? It seems that could do my fresh air distribution also? We do have a decent amount of above 95 and above 100 degree days here in the summer so AC is a want.
I have no direct experience with them, but if you have limited space for ducts, I would do high velocity before I did a multi-split ductless.
As your loads decrease, duct size shrinks, so it comes down to how you want to optimize your spending.
In 5b your heating loads are going to be greater than your cooling loads. Plus heat pump performance falls off in cold weather. So if you size the AC for your cooling load, it will be undersized for heating, use the radiators to make up the difference.
Note that a lot of what makes radiators so wonderful is most pronounced in leaky, drafty houses. In a tight, well-insulated house you don't get chilly spots in winter. In fact you have to worry about overheating, and the heat capacity of radiators becomes a liability as it causes them to overshoot. Turning the water temperature down is the solution.
Thank you for the response. We are getting longer winters here and do get down to 0F and sometimes below 0F for weeks. Although our summers are getting hotter and we have a decent amount of days above 95F so AC is going to be needed. Especially during Smoke season.
Radiators are still common in many areas, even modern homes. My MIL's house in Germany is all radiators, just a bit more modern ones. Tight house, but not well insulated. In the morning, you go downstairs to turn the TRVs on all of them from the 1 setting to the 3 or 4 setting. Nothing is automated. I love sitting next to the radiator. Even new builds tend to use radiators there.
Side note on that. German's have always had tight homes. Because of this, they believe you must "Luften" daily. Dead of winter - open all the windows for 15 minutes or we will suffocate! At least it kicks those radiators into high gear. This is where the tilt function on those tilt/turn windows gets used almost daily.