TRV Capacity

skyenglish

Hello, I am looking to replace all 16 of my radiator valves in my home with Smart TRV's. My question is, how do I determine if I should purchase large capacity TRV's or regular capacity ones? I just had my boiler replaced... with the same model and size as the original.

DunKirk Boiler Input BTU 299000; Max Relief valve cap. 245 MBH or LBS/HR; Steam PSI 15; Water PSI 30; Max Gax Pressure 14 in W.C.; Min Gas Pressure 5 in W.C.
Manifold Pressure 3.5 in W.C.".

Also, is there a recommended smart TRV/controller combination?

Thans for your response!

Jamie Hall

Didn't I see another thread like this recently?

EdTheHeaterMan

Jamie Hall said:

Didn't I see another thread like this recently?

About 5 minutes ago on "What's Wrong with this Picture"

LOL

nicholas bonham-carter

Is this steam or hot water?
One pipe or two?
What are you trying to achieve with the TRV’s, and how smart are they?—NBC

PC7060

When you say SmartTRV are you looking for electrical monitored and control like Honeywell evoHome?  

https://heatingcontrols.honeywellhome.com/products/valves/thermostatic-radiator-valve/Electronic-TRVs/

Are you in the US or Europe, makes a big difference

Paul Pollets

If it's a HW system, the boiler should have a mixing control with outdoor reset and use constant circulation to power the pump. I like to use a "smart" pump for optimal efficiency. The mixing control has a thermostat or sensor.

skyenglish

This is a two-pipe steam system... I would be nice if the people who know little to nothing about what I'm asking to hold their comments>

PC7060

Oh, you’re welcome! 

Erin Holohan Haskell

skyenglish said:

This is a two-pipe steam system... I would be nice if the people who know little to nothing about what I'm asking to hold their comments>

@skyenglish, they're just joking and mean no offense. @Jamie Hall was very helpful to you on that other thread, so I'm not sure where your comment is coming from here. The members of our community who are helping you are extremely knowledgeable and generous with their time. Please be respectful. That's our #1 rule here and I think you'll find that it makes this a great place to learn.

KC_Jones

I think it would help us help you if we had a better understand of what you are trying to accomplish.

Most 2 pipe systems already have capacity regulation build into them. So hearing someone having the desire to install TRV's across an entire system raises a red flag for me, a red flag of what may be wrong with the system.

Another red flag is hearing a boiler was replaced like for like. Most of the time these boilers were not properly sized and replacing like for like without doing and EDR survey could lead to another oversized boiler. Oversizing, especially on 2 pipe can cause all kinds of issues, including imbalance. In addition these systems are to run at a few ounces of pressure and an oversized boiler goes completely against that.

Boiler rated for 766 EDR, 16 radiators, is an average of 48 EDR per rad. I have old column style rads in my house and to get to 766 with 16 rads, each one would be 38" tall, 9" deep and 10 sections long. That is the average size. Not sure what you have, but wanted to mention it as it would be a shame to have paid for a brand new boiler that was sized incorrectly. Hopefully they at least piped it correctly and put a vaporstat on for that 2 pipe system.

And finally, to my knowledge, no one makes a smart valve that is rated to use on a steam system, this question has been asked quite a few times on here. If you have found a steam rated smart TRV valve, we'd love to hear about it and pass it on to others who have asked. The link posted above is for hot water systems only.

ChrisJ

I too assumed it was a hot water system.
I agree with @Erin Holohan Haskell and @KC_Jones

Kindness tends to go a long way.

skyenglish

@KC_Jones... Thanks for the response. I got the idea of switching to TRV from reading, https://heatinghelp.com/systems-help-center/rethinking-trvs-for-steam-systems/
It's a very old 7 bedroom/6 bath home built in 1879. What I'm trying to accomplish is separate heating control for each room with Smart TRV's. There doesn't seem to be a lot of knowledge of Smart TRV's with plumbers here in the States, most internationally. So, I was hoping someone here has been through the process of installing something like the Honeywell evoHome sysetm and had some experience with them.

Sorry for posting in the wrong group, I thought the main wall was for everything.

PC7060

"I was hoping someone here has been through the process of installing something like the Honeywell evoHome system and had some experience with them."

I explored the EvoHome option for my hotwater system and determined the systems is only sold and serviced in Europe. It also utilizes their power and Wifi standards (no surprise) so even if I was able to source to US, it would just be the beginning of the headaches..

I was unable to locate any similar systems in US market so ended up going with high volume manual TRV (Honeywell Braukmann) which worked fine without the Wifi remote tweaking by room feature. I typically adjust the rooms based on the control detent (Red button) located at the midpoint of the control, low side of detent is cool comfortable, high side of detent is warm comfortable. I'll also turn down spare bedroom room a notch or two which keep room around 65F. If we have guests, I turn knob back to midpoint and the temperature quickly responds.

Of course this is hot water so @Jamie Hall or @Steamhead are much better resources for TRV performance on Steam systems

KC_Jones

skyenglish said:

@KC_Jones... Thanks for the response. I got the idea of switching to TRV from reading, https://heatinghelp.com/systems-help-center/rethinking-trvs-for-steam-systems/
It's a very old 7 bedroom/6 bath home built in 1879. What I'm trying to accomplish is separate heating control for each room with Smart TRV's. There doesn't seem to be a lot of knowledge of Smart TRV's with plumbers here in the States, most internationally. So, I was hoping someone here has been through the process of installing something like the Honeywell evoHome sysetm and had some experience with them.

Sorry for posting in the wrong group, I thought the main wall was for everything.

The biggest issue you will encounter is you have steam, options become limited. The article you linked to is for 1 pipe systems that utilize the venting with the TRV.

The big challenge is volume. That US was overrun with forced hot air after WWII, it's cheap and in general that's what the US wants. In Europe with different standards and culture hot water is the name of the game, so you will see much more extensive support for these systems there. They don't have steam in Europe so everything revolves around hot water.

Hydronics in the US is a tiny part of residential heating and steam is a small subset of that.

I understand your desire for individual control, so I will reiterate my previous comments. Many 2 pipe systems had individual room control from the start through throttling valves on each radiator. If you post your system type, perhaps pictures of what you have at the radiators, you will get more comments and maybe find out you already have more than you think.

Are you having any balance issues currently? Things heating evenly? Nice low pressure operation?

skyenglish

@KC_Jones, thanks... but I think people are over thinking the Smart system. Instead of walking in the room and turning the TRV up or down, the Honeywell control unit attached to the TRV opens and closes it. It's controlled by a thermostat located in the room which is set to the desired temp. I was just attempting to seek out anyone in the US that has went through the setup. I think I will contact Honeywell directly as most of the control units work with both Hotwater and Steam.. Thanks much for your insights!

ChrisJ

I use TRVs on 5 out of my 10 single pipe radiators.
In my case, they only have to control air but I personally do not see an issue with adapting/swapping etc "Smart" heads onto them and allowing the rooms to change in temperature.

Especially in your case with a 2 pipe system.
I highly doubt Honeywell will be any help. Sadly, all I ever get from any large company are the generic "off the shelf" answers to any question with little to no thought.

If I was you, I'd start by buying 1 or 2 of the units and getting them in my hands to see if they can work, and what needs to be done if anything to adapt them. I.E. if the head will adapt to a US NPT unit, or if you need to adapt a BSPP or BSPT unit to your radiator etc.

PC7060

skyenglish said:

@KC_Jones, thanks... but I think people are over thinking the Smart system. Instead of walking in the room and turning the TRV up or down, the Honeywell control unit attached to the TRV opens and closes it. It's controlled by a thermostat located in the room which is set to the desired temp. I was just attempting to seek out anyone in the US that has went through the setup. I think I will contact Honeywell directly as most of the control units work with both Hotwater and Steam.. Thanks much for your insights!

PC7060 said:

the [EVOHome] systems is only sold and serviced in Europe. It also utilizes their power and Wifi standards (no surprise) so even if I was able to source to US, it would just be the beginning of the headaches..

Not so much the technical difficulty of installation for smart versus manual heads, both are are simple. Installing the actual TRV is the trickier part since the removing the old spuds can be a a challenge.

Sourcing for US market is where I ran aground. Let us know what Honeywell says.

motoguy128

Be sure you dont install a TRV in the room that has the thermostat. This has to remain the “master” radiator for the system. All others with TRV’s need ot be in rooms that require the same or less heat than this room. So it should be in a larger more centrally located room thats on the northern side of the house. Or it could be the room that last on the main that seems to heat up slowest.

To remove spuds, careful use of a reciprocating saw with a good metal blade makes short work of them. You cut off the end but leave 1” sticking out. Then make saw cuts radially in 3-5 spots carefully so not ot go too deep and cut threads. Then use a 24” pipe wrench try and loosen it. The “wedges” will collapse inwards slightly and it will spin right out. I’ve removed 3 now this way. I use a little extra tape and drop on the new spud. No leaks on steam or with 15psi water.

PC7060

I typically just use a spud wrench; only about 1 in 20 give me any trouble and then I use a channel lock if the spuds long enough. If not I cut the spud nut off then use a pipe wrench.

ChrisJ

I have 5 TRVs and 4 locations that are averaged by the thermostat and all 4 have TRVs.  

The interesting thing is if the thermostat is calling for heat, shouldn't the TRV be as well?

JUGHNE

skyenglish said:

@KC_Jones, thanks... but I think people are over thinking the Smart system. Instead of walking in the room and turning the TRV up or down, the Honeywell control unit attached to the TRV opens and closes it. It's controlled by a thermostat located in the room which is set to the desired temp.

Wouldn't the TRV be set to the desired temp as the tstat would be?

I do not see the advantage unless the TRV was hidden in a bookcase or cabinet.

Would the tstat start the boiler if off? The TRV would not.

PC7060

@JUGHNE - I believe the EvoHome system Honeywell sells in Europe / UK Utilizes the sensors inside of the smart TRV control head as a mini T stats located throughout the house. So each TRV is theoretically capable of creating a call for heat.  I’m not sure how that would work if the system isn’t piped primary secondary.  

If the boiler is configured with primary piping only, it’s especially important that a few radiators are locked open to ensure minimum boiler flow rates are satisfied in the rare but possible case that all TRV are closed.  

ChrisJ

JUGHNE said:

@KC_Jones, thanks... but I think people are over thinking the Smart system. Instead of walking in the room and turning the TRV up or down, the Honeywell control unit attached to the TRV opens and closes it. It's controlled by a thermostat located in the room which is set to the desired temp.

Wouldn't the TRV be set to the desired temp as the tstat would be? I do not see the advantage unless the TRV was hidden in a bookcase or cabinet. Would the tstat start the boiler if off? The TRV would not.

I didn't say you should i said you could.

In my case, the downstairs has 1 thermostat sensor and 5 radiators. It's basically 1 big open floor and 3 radiators have TRVs.  The 2 in my kitchen do, which I highly recommend.   On days where the oven is going those radiators never get steam.   It's a beautiful thing.

Using multiple sensors averaged means when the house as a whole needs heat it gets it and the TRVs determine how much.

It works much better than I expected honestly.  

JDHW

@PC7060

There are lots of options with Evohome.

At its simplest (1 zone) you buy an evohome controller and it acts like a wireless thermostat communicating with a receiver that switches on the boiler and pumps. If you have a multi-zone system with zone valves there as some wireless thermostats and receivers that will run the system just like a hardwired system. The evohome controller the communicates with the thermostats to coordinate the setting (time/temperature) from one location.

There are some battery powered TRVs that you put on individual radiators and these do have internal temperature sensors. They can be programmed into the system to act as a valve and link to another temperature sensor or to use the internal sensor. This a big selling point in being able to zone a house without needing to change the plumbing. In this arrangement there a wireless receiver that is used to switch on the boiler and pumps so if no rooms require heat the boiler will be off.

The normal way of dealing with lots of TRVs in a system is to add an automatic bypass valve (ABV) across the radiator circuits and to not use a constant delta-P pump. As the TRVs close the pressure difference across ABV/radiators increases, the ABV opens and maintain a constant flow through the boiler.

The core evohome system does not use WiFi - communication between the controller and and all the wireless bits operate at about 860MHz. The newer ones have WiFi and connect up to the Internet if that is what you want but the core operation does not require WiFi/Internet/Cloud services.

Regards
John

JUGHNE

So not really TRV's as we know them. Actually RCTRV's (remote control thermostat radiator valves) with modulating motor control.

The only tstat would be on the wall perhaps across the room.

JDHW

@JUGHNE

Your name is a more accurate on how they work if you use a separate temperature sensor.

Say you have a big room with three radiators you could put on of the "RCTRVs" on each radiator and then have a wall mounted "thermostat" in the same room. You setup the system and bind the three radiators to the single thermostat and ignore the internal sensors.

Alternatively, you could just designate the the temperature sensor in one valve as the "thermostat" for the room and bind all the valves to it.

Have a look https://youlearn.honeywellhome.com/uploads/documents/evohome_Installation_Guide.pdf if you want more info.

It is a neat system. Not sure why it not promoted in USA. Perhaps the prevalence of hot air systems and/or big loop systems that don't work so well with thermostatic valves.

PC7060

ChrisJ said:

It works much better than I expected honestly.  

Same with the TRV setup we have.  Like the ability to easily adjust the temp for each room. 

@JDHW - thanks for the info on the system. I did not know it used the old TV 800 MHz band for communications between the smart TRV and the base unit. 860MHz is approved for open use in Europe for IOT applications. The US has approved 920MHz for those applications so Honeywell would have to update the device for that frequency along making the required power modification. 

I’m guessing there is just not enough demand for them to create a US specific device. 

Jamie Hall

There really is no fundamental theoretical problem to controlling a radiator on two pipe steam with a valve -- powered or not, smart of not. There are, as others have mentioned, certain difficulties in adapting what is manufactured for Euopean use for use in the United States and Canada (and, I might point out, the other way around).

Except of one thing.

That is the relationship of boiler power output to heating system power demand. If there is a large number of radiators in the system, all controlled by individual or small group valves, it is quite acceptable to make a reasoned determination as to how many of those radiators will be on at any one time; there are good statistical approaches to this which can be used for large applications. However, for smaller systems -- such as the size of which we are speaking -- the statistical approach will not work well, as there will be a large probability that all the radiators will be calling at once -- and a perhaps equally large probability that none of them will. Therefore, determining the correct sizing for the boiler becomes pretty much a guess, and also as a result the prudent solution is to size the boiler for the total load. Further, there is the question of determining what is to control the boiler. In larger systems, this is often done with variations on timing circuits, often with the start of an on sequence being when steam reaches a certain (usually distant) location, and the length of the on sequence and the off sequence often determined by outdoor temperature. In smaller systems, this will not work weel, but control from individual radiators also will not work well, as if only one or two happen to be calling the boiler will be wildly oversized -- and worse, if the call from one radiator ends and then very quickly another calls, the result will be very inefficient short cycling.

How water systems do not present this problem -- if they are properly designed.

ChrisJ

Jamie Hall said:

There really is no fundamental theoretical problem to controlling a radiator on two pipe steam with a valve -- powered or not, smart of not. There are, as others have mentioned, certain difficulties in adapting what is manufactured for Euopean use for use in the United States and Canada (and, I might point out, the other way around). Except of one thing. That is the relationship of boiler power output to heating system power demand. If there is a large number of radiators in the system, all controlled by individual or small group valves, it is quite acceptable to make a reasoned determination as to how many of those radiators will be on at any one time; there are good statistical approaches to this which can be used for large applications. However, for smaller systems -- such as the size of which we are speaking -- the statistical approach will not work well, as there will be a large probability that all the radiators will be calling at once -- and a perhaps equally large probability that none of them will. Therefore, determining the correct sizing for the boiler becomes pretty much a guess, and also as a result the prudent solution is to size the boiler for the total load. Further, there is the question of determining what is to control the boiler. In larger systems, this is often done with variations on timing circuits, often with the start of an on sequence being when steam reaches a certain (usually distant) location, and the length of the on sequence and the off sequence often determined by outdoor temperature. In smaller systems, this will not work weel, but control from individual radiators also will not work well, as if only one or two happen to be calling the boiler will be wildly oversized -- and worse, if the call from one radiator ends and then very quickly another calls, the result will be very inefficient short cycling. How water systems do not present this problem -- if they are properly designed.

My system shuts down for 10 minutes if it hits 8" WC.   It's never happened yet