Heat distribution challenge

nystateofmind

I'm not a pro, so please excuse my ignorance as I describe this issue. We have a 5-zone hot water radiator system. One of the zones is to a separate guest house which has two floors (both on the same zone). The incoming pipe splits off into two serial loops, one for upstairs and one for downstairs. As it stands, the upstairs gets way hotter than the downstairs, which is undesirable. None of the radiators have valves so I can't regulate the temperature that way. I assume that's because turning one off would turn off the whole loop, like a string of Christmas lights.

Plan A was to split upstairs and downstairs into two separate zones with their own pumps, but while mechanically that would be straightforward, connecting the pumps electrically back to the control panel in the main house would be prohibitively difficult because it all runs underground.

Plan B (quick and dirty) was proposed by heating contractor: he installed a check valve on the upstairs loop as well as a gate valve. He thought the check valve on its own might address what he guessed could be the issue, and adding the gate valve was my suggestion so we could regulate the flow of water into the upstairs loop, or even shut it off completely as a stop gap.

It's just started to get cold this week and whether the gate valve is completely open or completely shut, the result is that the upstairs is still significantly warmer than the downstairs, and radiators upstairs are still getting hot (i.e. it's not just heat rising up). I'm guessing that means the gate valve is not doing what it is supposed to be doing but I haven't had the heating contractor back to check it out yet. The only other thing I can figure is that even though water isn't flowing through the upstairs loop, it's still getting warmed up by heat conducted from the downstairs loop, though that seems very unlikely.

I attached a diagram of the system and a couple of photos of where the check and gate valves are (they happen to be in the garage which abuts the guest house).

So, I'm hoping for thoughts on why this approach might not be working, and/or other ideas on how to (inexpensively) balance the heat between the floors short of moving forward on Plan A, which we haven't actually had fully scoped out and quoted, but based on eyeball assessments like "that's going to be very difficult", we veered towards the K.I.S.S. paths first.





Thanks in advance for any help!
Dan

nystateofmind

Just realized I posted this in "oil heating" which it has nothing to do with, but I don't see a way to delete the post. I am going to also post this in "radiant heating".

Jamie Hall

Well, it isn't radiant either. It's a perfectly normal hot water heating system.

First comment... gate valves are quite possibly the worst choice to regulate or balance flow between two loops. A ball valve is the best choice; a globe valve would be second best. A gate valve is must be either fully closed or fully open. The others can be throttled.

I'm kind of hoping that your diagram contains an error: that short length of pipe from the T on the return from the first floor to a T on the feed line for the second floor. If that pipe is for real, get rid of it.

Once you find a combination which will shut off heat to the second floor loop, however, you might be able to put a zone valve on that loop controlled locally by a thermostat.

HVACNUT

Can you post a pic of the circulator and its zone relay? Are there any extra low volt wires between the zone relay and the thermostat? If there are extra wires, zone valves can be installed and add one more thermostat.
And of course remove the gate and check valves.

nystateofmind

To Jamie -

The diagram is not accurate. The horizontal red pipe should stop at the rightmost vertical blue line, not extend past it. Sorry about that!

Thanks for the tip about using a ball valve, although I'm still left with the mystery of why there is still heat on the top floor with the gate valve shut off completely. But maybe the thing to do is put a ball valve in and if that doesn't fix it, then we know the root cause is elsewhere but at least we have the right kind of valve in there.

I'm chuckling at your last suggestion because I ran the same idea by my contractor and he said it wouldn't work. So, part of my problem is I may need a contractor with a different skill set since the gate valve was also his idea... But I'm not that worried about having thermostat control of the upstairs because we really only use the house when we have guests (thus my posting a few weeks ahead of Thanksgiving!) so I can live with a manually controlled system for a couple days at a time now and then.

Thanks,
Dan

Intplm.

Have you considered having your system piped with one radiator after another from the first to the second floor. That might help as well. With only one dedicated feed and one dedicated return? Is that something that can be accomplished with your current system.
Your drawing shows Tee's piped in, they might be robbing your down stairs radiators.

HVACNUT

I dont get it. Do you want to keep your over stuffed Thanksgiving guests cold or hot on the second floor? It won't be "Goldilocks" for them.
The manual valve idea is a hack job at best. Can you move the thermostat to the second floor? There are also wireless solutions. "Have thermostat, will travel."

Larry Weingarten

Hi, Have you considered radiator covers, or something to reduce heat output from the radiators? That would be a highly non-technical fix.

Yours, Larry

Intplm.

Pipe the radiators in a series loop. First to second floor.

nystateofmind

Replying generally to everyone: I think it would be pretty easy to pipe it as one series instead of two. We've only been in the house for two years out of it's 115 year life, so I wish I knew the history of why they piped it like this - maybe one loop didn't work and this was plan B? I did a rough calc and it seems like the radiators are theoretically balanced pretty well in terms of amount of radiation per volume, so that has a good chance of working I would think.

I hate to admit this, but I solved the original problem by discovering I had not fully tightened the gate valve (!). So at least I can turn off the upstairs now. And totally agree it is a hack job - we just wanted some cheap relief for Thanksgiving and save the elegant solution for later when we have more time and money.

Radiator covers would fall in the last ditch effort category the day the guests arrive, but in that scenario I'd probably just crack open windows

If piping as a single loop does not work well enough, then as pointed out there may be options to split into two zones and locally control the upstairs thermostat, so that's an avenue we can pursue if necessary.

Thanks all, this was very helpful!
Dan