Monoflow Continuous Circulation System

Sting wrote:

brckwlt wrote:

Poconoeagle wrote:i see!!! sounds like ya gotta go choke a valve or two and speriment till you can circulate consistantly and maintain a narrower temp defferential between the in and out

But im not sure what valves im chocking, the radiator valves?

one question at a time

this one

Do ALL the radiator valves in the house still open and close -- turn easily so you can limit the amount of energy drawn from the house loop?
IF YES -- then close them all and the thermostat will call the circulator to action and the house loop will be charges with energy and constantly circulate -- then when the boiler is at idle fire, the circulator is still pumping and the house begins to cool -- ONE at a time -- CRACK open the radiator valve ( about an 1/8 turn) on each COLD radiator waiting -- and this will be the hard part -- about 15 minutes before going to the next one. When they are all open just a crack each should begin to "feel" warm. Now WAIT and see if that is enough radiation to keep the house comfortable -- Likely it will not so now it becomes a search and destroy mission -- crank the radiator valve in what appears to be the most lived in space another 1/8 turn and WAIT an hour to see if that's enough -- and on and on and on --

You just balanced your system

or

And I like this one better -- but I want you to wrap you head around the paragraph above before we continue....

if there is a valve on either side of the main house loop circulator -- TURN IT CLOSED and open it just a crack -- now your globally limiting the boiler energy out put to the house loop that feeds each radiation source in the house - and your doing it equally thru the system. WAIT an hour and if the house is still cool and if the circulator is still pumping and IF the boiler is at idle fire -- crack (that valve or valves) open just a slight little bit more and WAIT again and keep that up until the system is pumping all night long and the house is comfortable. You may encounter an area or room that is warmer than another -- twist the RADIATOR valve (in that room or area) closed and do the dance detailed above on it to balance that area -- IF you do this at more than one radiator you MAY need to close the circulator valve -- remember the one we started with in this paragraph??? because why??? the TOTAL system energy use is being reduced by your individual radiator balancing and thus --- you need to reduce the TOTAL energy input as a whole into the house loop. --

once you have accomplished balancing your main loop and balancing you area radiation as described in paragraph two -- as the out door temperature get colder you will have to open the circulator valve just a smidge bit more to introduce more energy to carry the load and you will have to close it when the weather warms. This was the boiler tenders duty 100 years ago when out door reset controls were more expensive than hiring a guy full time for the boiler room.

You can do this and it don't cost NUTTIN. It just takes a lot of time to get it right at first -- then it takes a little time every day to keep it on track and when your comfortable with it you will be able to anticipate what valve you need to set where for the weather coming in tomorrow.

It no different than the knowledge of the old dead steam train engine operator that drove his traction motor by the fell and the sound of it. He learned by driving it - what position a valve or lever had to be in for the grade and the terrain of the tracks he was piloting his equipment. There were no ECM controls -- ti was a human -- and the had of ONE human that moved miles of freight with one locomotive. Your hand can heat your house too.

once you get this -- and if you get sick of it -- lets look at automatic outdoor reset or delta t pumping. But as I began -- OK not 80 posts ago but some time ago -- lets crawl lets walk and lets run in sequence -- or lets read some books to learn what we are doing so we can help ourselves and not depend of some dumb duck on the otter side of the public internet that cannot see in your basement.

Ok, I'm resurrecting this thread because I'm probably in a similar situation atm.

Given the advice you gave here for a monoflow system, would it work equally well with a two pipe system that was originally a gravity feed system when it was installed?

I'm trying to imagine why not, but it would seem that throttling the output off the boiler and balancing the radiators would be just as effective in either case.

It should be similar.

Pumping a gravity flow piping system is not a problem. Keep in mind that all of the radiators are piped in parallel. If the orginal plumber did a good job, they will also be fairly self balancing.

The radiator hand valves in a gravity hot water system usually have a hold drilled in the valve plug to allow a trickle of flow, so the radiator doesn't go stone cold and stop gravity flow.

Minor tweaking of rooms may be necessary for comfort. Patience will be a virtue.

steamup wrote:It should be similar.

Pumping a gravity flow piping system is not a problem. Keep in mind that all of the radiators are piped in parallel. If the orginal plumber did a good job, they will also be fairly self balancing.

The radiator hand valves in a gravity hot water system usually have a hold drilled in the valve plug to allow a trickle of flow, so the radiator doesn't go stone cold and stop gravity flow.

Minor tweaking of rooms may be necessary for comfort. Patience will be a virtue.

Good to know that for later

Thanks, I'm going to be busy this weekend turning knobs it seems.

I cannot believe anyone actually reads this crap I write

Sting wrote:I cannot believe anyone actually reads this crap I write

Lol.

I had a bad few moments thinking about thermal shock today, so I was doing some research here. This post addresses most of the issues that I would have had, if it were in fact a problem. The boiler design apparently isn't one where I have to worry too much about that, however the response time of the boiler due to the amount of water in the system has not been optimized.

The writeup you gave makes a lot of sense and I'm anxious to try it out.

Snow in SE PA tomorrow.

Sting wrote:I cannot believe anyone actually reads this crap I write

We don't, we simply love to gawk at yer avatar.

understood

Here's a problem.

I only have one circulator pump, and it's also the dump zone circulator.

It might be a bit difficult calibrating the flow rate so that I don't go over the high limit, and with the valve already constricted that might be a problem.

Exactly what are you trying to correct?

kstills wrote:Here's a problem.

I only have one circulator pump, and it's also the dump zone circulator.

It might be a bit difficult calibrating the flow rate so that I don't go over the high limit, and with the valve already constricted that might be a problem.

DO NOT just read one or two paragraphs of my drivel

and then assume you know how to balance your system or mine or his

One key point you need to keep in mind is the flow that your balancing has to equal both the engine ( your boiler ) and the load - or at least that's the target you want to get to.

Since I run my equipment with a variable input - well your mileage may vary - but you can do this with one pump. Just think it thru.

markviii wrote:Exactly what are you trying to correct?

Let me give you the full history, than we can discuss the best possible course of action.

My house was built in 1929, thereabouts (interestingly, it looks like it was going to be part of a very large development, the 'Wynn James Estates', but the depression hit and only 5 of the planned homes ended up being built). It's a structural brick home, with a framed second story. There are 26! windows in a house with a 32x24' footprint, but they have aluminum storms on them which means I have zero drafts. At some point, insulation was blown into the upper floor and the attic, so the home is reasonably well insulated for it's age.

I've replaced my old GE oil burner with a new LL 110K dual fuel boiler. The GE, which apparently was a 'Cadillac' boiler for it's time, looks to have been installed sometime in the 1950's. It also appears to have been tied into an existing two pipe gravity feed system, origins unknown. The mains in the basement are 2 inch, with 3/4 inch feeds and returns to the radiators, of which there are ten, 5 per floor. Frankly, were it not for the price of oil, the old system worked extremely well, was very reliable and could probably have kept running (with maintanence) until I died.

However, oil prices being what they are, I've converted over to coal. I've tied into the old system using 1 inch black iron for my feed and return, but using the bulk of the old mains to send the hot water up to the radiators. The issue this is presenting is that there is soooo much water that needs to be heated that the cycle times on the new boiler are pretty long. In oil mode, at 165k btu (approx), it took ~1 hour, 45 minutes for the circulator to start running without shutdown, it coal mode 9at 110kbtu) that extends out to 2 hours. The delta on the feed and return is as high as 100degrees, depending on how long it's been since the call for heat has gone out.

I learned a new term this week; 'thermal shock'. So in trying to figure out how to prevent that, I came across this thread. Sting's explanation on how to balance the system seems to solve two issues that I might have, that of dumping too much cold water into the system, and running the entire system more efficiently. So right now, I'm trying to work through the details on how to best accomplish that, starting with a system that only has one circulator hooked up. Running with the feed valve too far open allows too much of a delta to develop on supply and return. Running with it to restricted could potentially, I say potentially, not allow the dump zone to clear the heat from the boiler in time to keep the fire going in the grate.

Now, here's the second issue. For the record, I'm sure that these are resolvable, but it's fun to work through them (at least for me).

For some reason (probably because the damn aquastat display is upside down....that's not something someone can fix?) my low limit was set at 130f (HL-180f). I didn't notice this as a problem until this week. However, I did do some charting of burn times (I timed it from cirulator off, until the LL tripped the circulator again, then the circulator run time) at this temp to determine how long it would take for the system to come up to full circulation. The numbers were pretty linear, and I'll be I have a pretty straight line graph, but they were all done between the temperatures of 100f (low side with return) to 135f (max temp the boiler hit before the blending of the return water started dropping the temp). This was charted with all the valves on the supply and return wide open, and the boiler on max burn. All the radiators in the system came up to temp, not evenly, but by the time the 2 hours was up every radiator had warmed up and was putting out heat.

So last nite I changed my LL to 155f. Than, to start to balance the system, I restricted flow on the supply side of the boiler. In concept, for keeping the return blended better, this was working very well. I could run the system with the circulator going full out for hours at a time. The house came up to temperature, but very unevenly. In fact, I had two dead radiators (one of them being the bathroom, of course). In fact, al the radiators that were getting the most heat were in rooms I would need it the least.

I was able to close valves and start to re-direct flow to the radiators that were not getting heat, so this isn't a long term problem. However, I was surprised by the cycle time that the boiler had at the higher temperature settings (much longer than 2 hours) and how much less responsive the system was overall (heat concentrating in a few radiators).

So, that's what I'm doing. One question, based on limited testing so far, would be is it uncommon for different output temperatures to have a dramatic effect on how the heat gets distributed into the system? I've turned my HL to 165 and my LL to 145 to run some experiments today, but atm I'm changing too many variables at once without having enough knowledge of what might be happening. It could be that the restriction of the supply is causing the flow to favor a few radiartors over the others? Or it could be the water temp?

I understand, both for condensing and DHW, I want to run the temperature on the boiler higher. But if condensing is not an issue because of the solid fuel (thermal shock is apparently not an issue either, however better safe than sorry) would it be ok to run the boiler at say, 150HL and 130LL?

Next summer, I'm planning on ripping out the old 2 inch mains and going with 1 inch for the supply and return. By then, I'll have read Sting's books so that I can design the system as efficiently as possible. So this is a situation that I'm facing for just this winter.

But it's my new toy, and it's a puzzle, so it's fun to talk about.

Sting wrote:

kstills wrote:Here's a problem.

I only have one circulator pump, and it's also the dump zone circulator.

It might be a bit difficult calibrating the flow rate so that I don't go over the high limit, and with the valve already constricted that might be a problem.

DO NOT just read one or two paragraphs of my drivel

and then assume you know how to balance your system or mine or his

.

My comment was not a presumption of omniscience, it was an acknowlegement of uncertainty. If the DZ takes too long to clear the boiler temp back to the LL setpoint, the fire in the grate might go out. I have no idea how long that might take, but it presents an interesting challenge.

How about a new thread to discuss this and some pictures of your boiler piping?

markviii wrote:How about a new thread to discuss this and some pictures of your boiler piping?

Hehe, well, I'm not going to re-type all that.

Maybe a mod could switch that post out into a new thread?

As for pics, the best I could do is stick diagrams (no digi).

ok, start with some good reading on gravity systems: http://www.heatinghelp.com/article/332/ ... eating-FAQ

The good stuff is towards the end, when he talks about converting the system to forced circulation. It is important to note that the system was designed around a certain delta between the supply and return...most likely 20 degrees. Ideally you would have installed a bypass on the near-boiler piping to make this possible.