Water Temp When Hydronic System Is Not Running

109A_5 · May 5

" The 3250+ manual does not state anything about the “Plus” model having a 15 minute shutoff for the Hold-Off feature, so it seems it does not have that. "

On Page 9 see my post above.

HomeOwner7 · May 5

I’m reading an idronics article by Caleffi I found online. It discusses gravity systems, states:

“Many of these early systems contained an expansion tank at the high point in the system, often in the attic of a house.”

When I first bought my house, and the gravity heat system was still in place, there was an expansion tank in the closet of a bedroom on the 2nd floor.

The article continues on, states:

“This tank was usually sized to 1/36th of the total system volume…”

My memory is the expansion tank in the closet of my house held about 5 gallons of water.

I’m not really sure about that, but if true, then…

YEE HAW!

The “ocean” in the system in my house holds 180 gallons of water.

That can’t be right. Can it?

hot_rod · May 5

So basically you have a temperature problem or concern. Based on collected data.

Really the best, most important data is the boiler temperature at the return connection and the elapsed time.

There is not set in stone rule for how long the boiler would run before return rises above the fuels dewpoint, call it 130°. 10 minutes is a number the industry seems to agree on.

So what you want is a temperature solution for the temperature problem.

To accomplish that you need a control or device that monitors that return AND responds to the temperature.

As mentioned there are a number of methods used, An electronic fix would involve shutting or holding off the pump until the boiler warms sufficiently. This may work but a boiler with no flow doesn't get you an accurate return temperature number. Under the on and off pump control method, possibly frequently cycles until the temperature at the sensor location is satisfied. Based on some of your numbers this may happen through the entire heating cycle, if the thermostats satisfy before the boiler reaches a safe operating condition. I'm not fond of turning a motor on off at 15 minute intervals for it's entire life, if that is what results.

The mechanical or hydronic fixes include modulating the flow leaving the boiler at the rate required to maintain that agreed on return temperature.

A thermostatic mix valve as Ed has has shown modulates flow based on the non electric temperature sensor inside. So it slowly regulates flow, it is a thermal clutch, not a thermal switch.

Another option is a temperature sensing variable speed circulator that blends the flows based on temperature. This requires a control and additional pump, and more involved piping. A pic below with a tank (ocean of water :) as the load as opposed to piping and radiators that you have.

There are a number of piping arrangements shown for using a variable speed circ. You want the method that has the ability to "disconnect" the boiler from the load until it catches up. fig 7-15c

There is a slight difference in the piping between the two pump temperature controlled variable speed Fig 7-15a and 7-15c, do you see that?

Here is a pic of how a 3 way thermostatic mix valve works. The system load is very dynamic, changing minute by minute. In sone cases the valve allows return within minutes, under a high load or massive mass system, it could take 10 minutes or much longer, every application is different.

The boiler is running steady state condition during this period, the most efficient state, other than completely off :) The pump is also running non stop circulating one or both loops, the boiler and the system.

TerrS · May 5

@HomeOwner7

So according to Google

How does the water content in a 3-inch iron pipe compare to other pipe sizes?

A 3-inch iron pipe has a water content of about 2.31 gallons per foot, which is higher than smaller pipes like 1-inch (0.34 gallons/ft) or 2-inch (1.36 gallons/ft) pipes but lower than larger pipes like 4-inch (5.44 gallons/ft) or 6-inch (13.6 gallons/ft) pipes. The water content increases with the pipe's diameter.

So you could walk around your basement calculating total pipe length to get a number and then probably 2 to 3 times it to account for all the water in the radiators and pipes.

But yes you have lots of water

109A_5 · May 5

" I'm not fond of turning a motor on off at 15 minute intervals for it's entire life, if that is what results. "

Why would it do this ? That is not what I get from the Hydrostat manual, if that is what you are referring to.

TerrS · May 5

So how i read the hold circulator function is it will hold energizing the pump until broiler is 125 degrees, as the cold water is introduced back into the system and bolier temperature falls below 115 degrees it will hold again. But this looping cycle only last 15 minutes.

Which actually isn't bad, but in @HomeOwner7 case probably not long enough to keep the boiler temperature raised. But, if you are always adding in 125 water, it might have helped, however his bypass loop is AFTER the pump, so the only water you are heating is boiler tank.

HomeOwner7 · May 5

TerrS:

Thank you for the info. I’ve posted photos of the inner workings of the Hydrostat below.

hot_rod

Thank you for posting the detailed info. I’m anxious to read thru it. I should have time to do that over the next few days.

109A_5:

Thank you for having noticed that our Hydrostat 3250 Plus “Installation Instructions and Operating” manuals do not state the same things. This gets interesting.

The Manual you posted an image of states:

“Circulator Hold Off will expire after 15 minutes”.

But my Manual (below) omits that statement altogether.

Additionally:

The Patent Numbers shown on the front cover of our Manuals also differ.

Your Manual references:

Patent No. 8,931,708, 8,844,834; 7,891,572; others pending

But my Manual (below) references:

“Patent No.7,891,572.

Therein lies the confusion.

I phoned HydroLevel to find out if the 3250-Plus, the model installed in the hydronic system in my cellar, does - or does not - have the 15 minute Hold Off feature.

Per the HydroLevel Tech: Yes, the model I have definitely does have that feature. He added that feature has been in place for the last 10 years.

It seems what has happened is certain features on the Hydrostat 3250 Plus were changed but the model number was not updated, remained the same.

So, I guess I have the wrong Manual. It must be outdated.

Note that the label on the Hydrostat in my cellar (see photo below, lists -five- patent numbers.

So I want to be sure I have the correct Manual. When I asked the HydroLevel Tech if the correct Manual could be emailed to me, he said I can find it on the HydroLevel website. When I asked how can I be sure I’m getting the correct Manual for the exact model Hydrostat I have, he suggested I search for the manual for the “new style” HydroStat 3250-Plus. I’m seeing only one Manual for the 3250-Plus on the HydroLevel website, so that must be the one and for sure, that Manual does state:

“Circulator Hold Off will expire after 15 minutes”.

Additional Info Regarding the Hydrostat 3250-Plus installed in the heating system in my cellar:

Label on inside door of Hydrostat in my cellar

Note: Five Patent Numbers are referenced.

Control Guts (so to speak)

With settings the installer company made.

TerrS · May 5

@HomeOwner7

Thanks those pictures help. Except those wires in front of economy blocked what its set to? So just guessing from where its pointing maybe 4 or 5. Which isn't good in my experience. Its better to set to 1 or maybe 2.

I would definitely try the circulator hold and economy 1 or 2 and see how your boiler reacts.

HomeOwner7 · May 7

Something odd having to do with posts on the forum has happened.

I typed my comment into the "Leave a Comment Window", but then it became unnecessary to post it, so I wanted to delete it, and I’ve tried about 10 times to do that, but nothing I do permanently removes it from the "Leave a Comment" window.

I made sure I had closed completely out of Heating Help website on both my home computer and iPhone after deleting the comments. My thought was maybe it's necessary to log out of the forum on both devices, not doing so may possibly embed the comment I'm trying to delete, making it impossible for me to remove it - but that didn't work either. The comments reappear every time I go back and open the forum.

So, I'm going to have to take the last resort method. I've again deleted the comments from the "Leave a Comment" window, typed this a new comment (this one) into the “Leave a Comment” window, and am posting it. Here goes.

If you see any comments after this, please disregard them.

109A_5 · May 7

Don't worry about it, just delete the text you don't want (or backspace) with your next actual wanted post.

Or save it as a Draft then click on your account picture (upper right)

then click Drafts, then click on

then delete the Draft.

Water Temp When Hydronic System Is Not Running

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