Moving to continuous circulation with TRVs

skiereric

Over the summer I installed TRVs on all of my European-style panel radiators.

The goal was to have better control over the room temp in different parts of my house.

I realize now, that a variable speed circulator should be used given the changing demand, and since I do not have a pressure-activated bypass.

I am going to be installing an Alpha2 15-55F to replace the existing UPS 26-99 FC. Head=7.75, Flow = 10.2 GPM.

My boiler is the Weil Mclain 97+ 155 (https://www.weil-mclain.com/sites/default/files/field-file/wm97-ct-manual_1.pdf)

Currently, the circulator starts to run when there is a call for heat.

My question: how do I get the circulator to run continuously during the heating season?

Also, am I on the right track?

Jamie Hall

You are. There are a number of control strategies to do this sort of thing, but if all the heat is basically controlled by the TRVs, perhaps the best -- if your boiler will allow it -- is to run the boiler continuously, or nearly so, off an outdoor reset curve, and run the circulator any time the boiler water is warm enough.

skiereric

Thanks, I should add my boiler is piped with primary/secondary with DHW having priority.
My house has a high demand for DHW a few times a day, which results in the boiler switching over to DHW, the circulator stopping, and then starting up again when the DHW call is satisfied.

I would like the circulator to be always operating even during DHW calls.

Jamie Hall

skiereric said:

Thanks, I should add my boiler is piped with primary/secondary with DHW having priority.
My house has a high demand for DHW a few times a day, which results in the boiler switching over to DHW, the circulator stopping, and then starting up again when the DHW call is satisfied.

I would like the circulator to be always operating even during DHW calls.

Why? All that will accomplish is slow down recovery for the DHW.

hot_rod

How is the indirect piped and pumped? With enough boiler power, and adequately sized pump and piping, you should recover the DHW quickly, 10- 20 minutes.
It depends on incoming water temperature, size of tank, recovering while still running DHW, etc.

Lowering the dhw load may help, lower flow shower heads? stagger dhw loads.

Raise the indirect operating temperature and add a mix valve, for more drawdown.

skiereric

Jamie Hall said:

skiereric said:

Thanks, I should add my boiler is piped with primary/secondary with DHW having priority.
My house has a high demand for DHW a few times a day, which results in the boiler switching over to DHW, the circulator stopping, and then starting up again when the DHW call is satisfied.

I would like the circulator to be always operating even during DHW calls.

Why? All that will accomplish is slow down recovery for the DHW.

Trying to avoid the sounds that occurs from the pex flexing against the floors/studs when the circulator first starts up. After a minute or two after the circulator starts up it is completely silent.

skiereric

hot_rod said:

How is the indirect piped and pumped? With enough boiler power, and adequately sized pump and piping, you should recover the DHW quickly, 10- 20 minutes.
It depends on incoming water temperature, size of tank, recovering while still running DHW, etc.

Lowering the dhw load may help, lower flow shower heads? stagger dhw loads.

Raise the indirect operating temperature and add a mix valve, for more drawdown.

Yes, the call for DHW takes no more than 10 minutes. What is annoying, is that I hear the creaks of the pex against studs/flooring whenever the circulator starts up, this lasts for 1 minutes or so any then becomes silent.

Jamie Hall

Kind of a tradeoff there, isn't it? Either the annoying sound -- or much longer recovery (perhaps in the hours) for the domestic hot water.

hot_rod

Actually the expansion tank connected at the inlet of #5 circulator would establish a nice PONPC for all those circs.

JohnNY

skiereric said:

Jamie Hall said:

skiereric said:

Thanks, I should add my boiler is piped with primary/secondary with DHW having priority.
My house has a high demand for DHW a few times a day, which results in the boiler switching over to DHW, the circulator stopping, and then starting up again when the DHW call is satisfied.

I would like the circulator to be always operating even during DHW calls.

Why? All that will accomplish is slow down recovery for the DHW.

Trying to avoid the sounds that occurs from the pex flexing against the floors/studs when the circulator first starts up. After a minute or two after the circulator starts up it is completely silent.

I have some experience with trying to correct this. The creaky pex thing is a result of temperature change, not flow. I failed at trying to quiet a creaky staple-up job by having the pump run longer at a greater temperature delta. When it was time to bring the RFH up to temp though, the pex creaked away. There's a solution to the noise in every case but my guess is this isn't going to get it done for you and you might want to to reassess the situation.

pedmec

figure 57 is the wrong diagram as that is zoning with circulators. figure 54 is a better depiction of what you have. trv's are zone valves.