Need Help

Constantin

TRVs on the cast iron stuff... that'll keep them in check.

Another option is to put in another zone valve just upstream of the cast iron stuff, putting them on a separate zone. Perhaps with a tempering valve to make them rob less heat / run cooler.

A fixed ratio mixing valve there could also work... though the powder room would probably have to be op a separate zone or it'll be cold in there.

Wayco Wayne_2

Looked at a problem job

today done by another contractor. Everyones trying to be nice and find the end to this job. There are problems with the hydronic heating. The original house had cast iron radiators and was once a gravity system. Still has the big pipes and the over sized CI (cast iron) rads. A 2 story addition has been added on the back of the house. All copper fin baseboard in the addition. There is a cast iron boiler with 2 zone valves and one circulator. (not pumping away. hmmph!) When I arrived the boiler was chugging along at 180 degrees. The addition zone, Zone 2, was calling for heat. The orignal house, Zone 1, was not. I turned on Zone 1 and while I watched the cast iron rads stripped the system of all it's heat and the boiler thermometer dropped to 100 degrees. Yikes! A little thermal mass in those over sized CI rads eh? If I had designed this originally, I would have put the CI rads on a seperate circuit with a VSI control taking care of it. To complicate things Zone one has a few copper fin baseboards installed where radiators used to be, and to 2 added rooms to the front of the house. What is needed though, is an inexpensive solution. Any ideas?? WW

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Dave DeFord_4

Maybe a timer...

If you put a timer on the cast iron zone would that keep that zone from robbing all of the heat from the other zone? When the thermostat called for heat it would trip the timer for a while, maybe 5-15 minutes depending on the load, and then the timer would shut that zone down even if the t-stat was calling for heat. Let the CI flywheel for a while as the baseboard continues to circulate. Then after a while, maybe 15-45 minutes the timer would reset. If the first zone t-stat was still calling for heat the cycle would repeat. It would take some experimenting to get the settings right and it may have to be changed in the spring and fall when the loads are changing but it seems like it might work. Maybe you could do the same sort of thing sensing the boiler temp. Anybody ever tried anything like this?

lchmb

another thought...

How about repiping at the boiler and going with an injection style system?

Brad White_48

Optimum Solution

I agree with Constantin's TRV suggestion but would take that a little further. Forgive the obvious but the mixing of CI and Fin Tube on one zone is a no-no under Hydronics 101, as is the "not pumping away". Not to beat anybody up, just stating the premise.

I would make it pump away, no short-cuts there. I would add TRV's on the CI at a minimum and then on all of the FTR branches. This will do the next best thing to having each type of radiation on their own zone. Absent that, can the CI be grouped onto their own zone(s) as you suggested?

Next, I would set the circulator up for constant circulation with a PRV bypass and omit the zone valves. Let the boiler fire to space temperature and let the TRV's do their thing.

Absent that, decouple and constant circulation with TRV's and injection, as suggested below by Lchmb. TRV's are the biggest help in this case though, IMHO.

Brad

Wayco Wayne_2

I was thinking

of re-grouping the emitters so cast iron and baseboards are as seperate as possible to begin with, because basically there are 2 different water temps needed. I would then give the Cast Iron zone it's own circulator and set it up for constant circulation and use the zone valve as an injection device. I could put a circuit setter on the return of the injection loop so I don't inundate the boiler with cool water. I'll work on a new drawing and post it later. I like the idea of the TRV's but inexpensive is the rule in this case. WW

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Weezbo

danfoss on the powder room TRV on cast iron?

with an i series S from the supply to the return...

the additional baseboard on the zone 2 i think might need some sort of control too.it is still possible to get threaded monoflows....

Wayco Wayne_2

Here's what

I would like to do if it were up to me. (attachment below) I feel bad for the installing contractor though, and hope he can work it out and do the work himself. His work looked nice and he took good care to make things look OK. He just didn't have the designing experience to deal with the situation. WW

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Brad White_9

I think you nailed it, Wayne

Not to be picky but I know you will clean up the P/S interface at the beginning of the CI loop. (Would work as two pumps in series is what I see. Do you need that first circulator, the one next to the circuit setter? I do not see why you would need to move the water twice.

But the essence of divorcing the radiation types (which I thought was an expense to be avoided) may well be the best solution. And the well-motivated original contractor will be better for it thanks to you.

Paul Rohrs_4

Injection Mixing

Brad,

I think that is his injection mixing setup for the zone of CI rads. I would move the tee's closer for fear of reprisal from the hydronic community, but it will succesfully provide reset to that zone.

Regards,

PR

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Brad White_9

Thanks, Paul

Of course you are right. I saw the "straight-shot" versus a tee so was thinking "series" -and missed that there was no other modulating device such as a valve. It is the right thing to do..

Anyway, no criticism of Wayne and his work was intended, -nor were any animals harmed in the making of this correspondence...



Brad

[Deleted User]

Wayno...

Consider the use of an ESBE Thermic valve.

It goes on the return, protects the boiler and allows what ever hot water is available to go to the zones based on availability and call. Make sure your heat generators equal your heat emmiters.

That would be the least expensive "fix" to keep things hot and flowy.

Your fix is the "right" way to fix things, but if price is a consideration, the ESBE is a cheap 'fix'.

What always kills me about these jobs, is that the consumer doesn't want to spend ANY more money on their "heat" than necessary. Guess they need to save their dollars for the Benz in the driveway...:-)

Make sure the other contractor learns about THIS place and make sure he comes here and learns so you don't end up having to keep following after him, "fixing" systems.

Just because he knows how to run pipe and solder does not make him a hydronic heating expert:-)

ME

Wayco Wayne_2

Thanks everyone

I met with the installiing contractor last night and all went well. He was a very bright young man eager to do things right. I could hear the light bulb go on when everything dawned on him. Very cool to get paid as a consultant. My back didnt hurt at all doing that kind of work. WW

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