Keeping boiler return temp lower as TRV’s close down

[Harry Bloomfield]

A bit like Harry, I have a condensing boiler (all be it a heat only boiler with no internal pump control) with existing controls, all be it “dinosaur age” controls. Simply consists of a wireless room stat, timer and TRV’s. I have no intention or desire to spend hundreds of pounds upgrading the controls for something which will take years to break even on with savings. I don’t even think my BG 330 has the capability for things like weather compensation? Thats what our last Gas Safe man said at the last service anyway. Who am I to disagree? If that’s false please let me know.

Anything done in the way of improvements, has to have a financially worthwhile or comfort reason, or it is not worth doing. I was in the situation of a forty year old system, fitted with a later replacement heat only condensing boiler, which was unreliable and operating on very basic controls. The boiler was unreliable, so I decided time for a new, much more modern one which I installed still on my original very basic controls, with it's constant wide swings in temperature, as the boiler cut in and out. Whilst the system was drained, I added wax TRV's too.

Having got that far and heat back on, I looked at options for upgrading my old control system and what my new boiler directly supported. I bought and installed a complete new system, which included an outdoor sensor weather compensation, plus manual compensation for the environment it was in. I then spent weeks tweaking it and trying it's various settings, until I got out of it just what I wanted - a system which was unnoticeable in operation. The lack of over-shoot, was most noticeable when the stat is adjusted to increase the temperature - now it comes on, then just gently ramps down as it nears the demanded temperature, rather than over-shooting the setting.

Once at temperature, it just holds it there with a steady trickle of heat input, rather than either heat or no heat. So a big bonus in comfort and some economy.

I was always under the impression that only heating some spaces led to more heat loss than heating it all up together?

In my opinion, that depends upon how big a home you have, how you use it and how well insulated it is. I have a medium to large sized 3 bed 1955 semi, which I upgraded over the years with CWI, DG fixed all of the many air leaks and added properly controlled ventilation. It was horrendous when I first moved in, absolutely freezing in winter. We generally have all internal doors open, unless it is very cold. Unless you have a big rambling home, with sections unused most of the time, there is not much point to zoning. If zoned to have the upstairs off in the day, heat will rise anyway.

On and off, plus actual temperatures are simple - It is always on. Night temperature is set at 16C, it never gets that cold in here, day temperature is 18C, which I might nudge up to 20C if we feel chilly.

I just want to work with the existing controls and boiler to make them work a little better - even gaining a couple of percent worth of efficiency at the boiler if I can keep the return temp at 55 degrees or lower for longer.

if my rooms are over shooting, what can I do about that? Balance down a bit?

If you don't have one already, you cannot beat having a boiler which is able to ramp it's output down to match the needs of the house. The more it can ramp down the better. Even better with a control system which can predict 'tell' the boiler how much output is needed in a heating cycle.

As a quick and simple fix and an idea for the experts to consider - Add a pipe thermal switch /stat. set at what you consider to be a maximum return temperature and wired to inhibit just the boiler? You can buy clamp on to the pipe type stats. and it would go right next to your boiler, but might make you boiler cycle even more?

 

[ericmark]

Wax TRVs are dead end, 80's technology.

5 years ago I would have agreed, I fitted 4 electronic TRV heads in mothers house, they showed target and current, so if current exceeded target I would turn the lock shield down a tad, and they bar for living room with bay window were spot on.

So on selling house new owners did not want them, so old wax things went back on, and they also worked spot on.

The problem is *123456 marked on a TRV is useless. If you get a TRV and test if open or closed by blowing through it, you find the range is large. Looking at around 3 to 4 degrees fully open to fully closed, and at 20°C likely between 2 and 3.5 on the scale.

If the lock shield is set correct, then you just play with the dial and try between 2 and 3 until room at 20°C. But if lock shield not set, then catch 22, can't set TRV until lock shield set, can't set lock shield until TRV set.

And of course the boiler must be running, if the wall thermostat turns off, then again can't set TRV or lock shield.

How a heating engineer sets the lock shield I don't know, but it seems most installations they are left wide open. So the occupant is left with three controls and no real way to set them.

Then we add to that rooms only used for a short time. Clearly if the programmable TRV is set to move 16°C to 20°C at 4 pm nothing will happen unless the boiler is running. However drop the wall thermostat 0.5°C at 3 pm and raise 0.5°C at 4 pm and in the main the boiler will run.

I have today 9 programmable TRV's, but the boiler is oil so on/off. But the biggest problem is where to fit the wall thermostat.

Kitchen has outside door and a cooker, so that out, dinning room hardly used, and large patio door, living room also patio door, and gets morning sun so can get quite warm without the heating running, hall has stairs, and outside door, so really want multi thermostats so if either hall or living room cool boiler will fire.

So EvoHome, Wiser, Tado, even Hive all have coms between TRV and wall thermostat so can in real terms monitor multi rooms. I got the odd one out, Nest Gen 3, Nest have remote sensors so it can monitor 4 rooms, but only with US version this is not the British Nest. So do I wait and see if Nest releases the temperature sensors in the UK, or rip out and start again?

And this is the problem, once one has committed to one system to change becomes expensive. So we try and muddle on and hope there will be a update. This happened with Hive, the original Hive was useless, then the linked TRV heads were released, which as long as main wall thermostat is below 22°C it can cause the thermostat to call for heat.

I looked at the Crème de la crème, the Ivector Myson fan assisted radiator, and with my oil fired boiler it would work, although expensive, but really it needs the piping in series not parallel with modulating boilers, i.e. no restriction on flow, the fan speed varies with 6 options if one includes off, plus can be used to heat or cool, but when one looks at the price of the building management system, it becomes rather silly.

So having a fast response time, means keeping the water used to transfer the heat down it minimum, and the matrix as light as possible. We jump into the car, and with a petrol within ½ mile the heater is working, the climate control keeps the cab at temperature set within 0.5°C and with a duel matrix ivector the home can have same level of control.

But if I remove the cover off my open fire I can burn the abundance wood around my property and enjoy the pleasure of a real fire. And do all the dusting, emptying of ash, and all the other associated tasks.

I prefer to take this wood to where I work and use it to get the coal fire burning in a real boiler, one that actually boils water, with the hired engine super heated steam, and pull the visitors children to see father Christmas at the North Pole (a station further up the line). The carriages in the main have heaters which use steam, giving loads of ambiance as a total loss system, as the steam envelopes the carriages it heats.

Only problem is I am doing car part duty so darn cold, but seeing the children's faces after the visit is worth it. If worried about ecology we do have two 22 kW car charging points.

 

[BlueLoo]

I didn't know nest has

5 years ago I would have agreed, I fitted 4 electronic TRV heads in mothers house, they showed target and current, so if current exceeded target I would turn the lock shield down a tad, and they bar for living room with bay window were spot on.

So on selling house new owners did not want them, so old wax things went back on, and they also worked spot on.

The problem is *123456 marked on a TRV is useless. If you get a TRV and test if open or closed by blowing through it, you find the range is large. Looking at around 3 to 4 degrees fully open to fully closed, and at 20°C likely between 2 and 3.5 on the scale.

If the lock shield is set correct, then you just play with the dial and try between 2 and 3 until room at 20°C. But if lock shield not set, then catch 22, can't set TRV until lock shield set, can't set lock shield until TRV set.

And of course the boiler must be running, if the wall thermostat turns off, then again can't set TRV or lock shield.

How a heating engineer sets the lock shield I don't know, but it seems most installations they are left wide open. So the occupant is left with three controls and no real way to set them.

Then we add to that rooms only used for a short time. Clearly if the programmable TRV is set to move 16°C to 20°C at 4 pm nothing will happen unless the boiler is running. However drop the wall thermostat 0.5°C at 3 pm and raise 0.5°C at 4 pm and in the main the boiler will run.

I have today 9 programmable TRV's, but the boiler is oil so on/off. But the biggest problem is where to fit the wall thermostat.

Kitchen has outside door and a cooker, so that out, dinning room hardly used, and large patio door, living room also patio door, and gets morning sun so can get quite warm without the heating running, hall has stairs, and outside door, so really want multi thermostats so if either hall or living room cool boiler will fire.

So EvoHome, Wiser, Tado, even Hive all have coms between TRV and wall thermostat so can in real terms monitor multi rooms. I got the odd one out, Nest Gen 3, Nest have remote sensors View attachment 253283 so it can monitor 4 rooms, but only with US version this View attachment 253284 is not the British Nest. So do I wait and see if Nest releases the temperature sensors in the UK, or rip out and start again?

And this is the problem, once one has committed to one system to change becomes expensive. So we try and muddle on and hope there will be a update. This happened with Hive, the original Hive was useless, then the linked TRV heads were released, which as long as main wall thermostat is below 22°C it can cause the thermostat to call for heat.

I looked at the Crème de la crème, the Ivector Myson fan assisted radiator, and with my oil fired boiler it would work, although expensive, but really it needs the piping in series not parallel with modulating boilers, i.e. no restriction on flow, the fan speed varies with 6 options if one includes off, plus can be used to heat or cool, but when one looks at the price of the building management system, it becomes rather silly.

So having a fast response time, means keeping the water used to transfer the heat down it minimum, and the matrix as light as possible. We jump into the car, and with a petrol within ½ mile the heater is working, the climate control keeps the cab at temperature set within 0.5°C and with a duel matrix ivector the home can have same level of control.

But if I remove the cover off my open fire I can burn the abundance wood around my property and enjoy the pleasure of a real fire. And do all the dusting, emptying of ash, and all the other associated tasks.

I prefer to take this wood to where I work and use it to get the coal fire burning in a real boiler, one that actually boils water, with the hired engine super heated steam, and pull the visitors children to see father Christmas at the North Pole (a station further up the line). The carriages in the main have heaters which use steam, giving loads of ambiance as a total loss system, as the steam envelopes the carriages it heats.

Only problem is I am doing car part duty so darn cold, but seeing the children's faces after the visit is worth it. If worried about ecology we do have two 22 kW car charging points.

Didn't know nest was a thermostat/zone system only. That makes it pretty outdated today.

 

[Harry Bloomfield]

Then we add to that rooms only used for a short time. Clearly if the programmable TRV is set to move 16°C to 20°C at 4 pm nothing will happen unless the boiler is running. However drop the wall thermostat 0.5°C at 3 pm and raise 0.5°C at 4 pm and in the main the boiler will run.

I have today 9 programmable TRV's, but the boiler is oil so on/off. But the biggest problem is where to fit the wall thermostat.

From all that, I am not sure Eric, whether you agree with wax TRV's or not. I like there simplicity and they do all I want from a heating system, without needing any outside sources to make them work (Internet). When you set them - you have to keep in mind, you are not so much setting the temperature you want, as the maximum temperature you want in the room the TRV is located.

SWMBO sleeps in her own bedroom at the back of the house. Every time I had need to go in there, I noticed the TRV was set on it's max/wide open, so I would tweaked it down to something a bit more sensible - rinse and repeat. Sometimes she would be doing an early shift and be in bed at 9pm, but the heating continues on it's higher room temperature setting until 11pm.

Last month she complained that it was so hot in that back bedroom, she couldn't sleep - at the same time she was complaining that the radiator was too cool. She equated the radiator being cool, with the room also being too cool. So I tackled her on her turning the TRV up to max and explained that turning it up, doesn't necessarily make the radiator warmer, it is just there to limit the room's temperature. I'm not sure she understood, but I just said don't mess with it, if the room itself is warm enough. If the room isn't warm enough turn it up a small fraction.

Yes, I have just checked and miracle - it is on 3.5. I set it on 4, so she has nudged it down a touch more

 

[BlueLoo]

Smart trvs and a wall stat would be a great help to her. (not being smart here btw).
Perhaps buy your wife a 10£ thermometer from amazon.

They are great in letting you know if its you, or the room which is cold.....

 

[Harry Bloomfield]

Smart trvs and a wall stat would be a great help to her. (not being smart here btw).

Absolutely not going to happen. Now I think she knows how it works, there have been no more complaints.

Perhaps buy your wife a 10£ thermometer from amazon.

They are great in letting you know if its you, or the room which is cold.....

No need, plenty of room temperature measurement and logging already here.

 

[ericmark]

My bluetooth eQ-3 work well at £15 each, can't see point of using wax heads.

 

[BlueLoo]

My bluetooth eQ-3 work well at £15 each, can't see point of using wax heads.

Lots of old people who are used to things a certain way (not always tho') like the on-off approach to heating they have grown up with.

Std TRVs are mostly a fire n' forget weapon in the heating Arsenal which enables the user to interact with the heating as little as possible whilst having the illusion of control and preserving the on-off mentality.

Before i change to smart rads, i read a few blogs on the smart vs dumb trvs and mostly, they couldn't see the need for change if the user had trvs already installed.

I was swayed by the argument but wanted a better user interface with the rads so dove in anyway. (Wiser).

I can tell you that this viewpoint is utterly incorrect. If you can manage a small amount of input into the system, the outputs are fantastic. It has made me look at std wax trv/2 zone systems as something out of the Victorian era.

It will become std practice in short time i believe. From scratch install costs must be comparable. You dont have zone valves (ex HW tank). You don't have zone wiring or thermostat wiring. Smart systems are less labour than std which is where the money usually is spent.

Zoning, trvs, zone stats, etc. Its a dead tech.

 

[ericmark]

Wiser TRV's are claimed to have built in algorithms that work out room size. And how long it will take to heat. So are about top of the range.

But to use the TRV control the boiler must run, great with modulating boiler, not so good with on/off control.

 

[BlueLoo]

Wiser TRV's are claimed to have built in algorithms that work out room size. And how long it will take to heat. So are about top of the range.

But to use the TRV control the boiler must run, great with modulating boiler, not so good with on/off control.

The boiler runs itself. The controller tells the boiler when based on info from the trv sensors.

Wirks great with my non modulating boiler. The Wiser system can work with most types of boiler.

 

[Harry Bloomfield]

My bluetooth eQ-3 work well at £15 each, can't see point of using wax heads.

Bet my TRV4's, which don't need batteries, are still working long after your eQ-3's have expired. The point is, that they are simple tech, which just work without needing any excessive tech to support them.

 

[BlueLoo]

Bet my TRV4's, which don't need batteries, are still working long after your eQ-3's have expired. The point is, that they are simple tech, which just work without needing any excessive tech to support them.

I changed all of my TRV's because out of the 11 in the house, when i checked, only 1 was still serviceable. The rest had all failed.
I was quite surprised at the death rate tbh. I had no idea they were broken either. I just assumed the poor temp control in the house was typical of the wide control band the TRVs have.

Std TRVs need MORE tech to support them than smart TRVs. They need zone valves, the associated wiring, stat wiring etc. They are also not intuitive and need a certain degree of understanding on how to use them by the inhabitants which can be difficult to grasp as per your own example.
I'm all for simple tech but sometimes simple is just that when the reality of the industry has moved on to the benefit of all.

 

[Harry Bloomfield]

Std TRVs need MORE tech to support them than smart TRVs. They need zone valves, the associated wiring, stat wiring etc.

Only if such a system as zoning is a requirement.

They are also not intuitive and need a certain degree of understanding on how to use them by the inhabitants which can be difficult to grasp as per your own example.

That is simply not true is it? I would much rather attempt to explain to my partner how a to operate a TRV4, than how to set up and operate a fancy bluetooth wireless unit times and temperatures. I am well used to tech, but even I would expect to have to sit with the manual for an hour or two to understand them. Put it in front of my partner and her eyes would glaze over.

 

[bernardgreen]

Std TRVs need MORE tech to support them than smart TRVs. They need zone valves, the associated wiring, stat wiring etc.

Smart TRVs which influence the operation of the boiler require a secure and reliable wireless communication system to be in place.

That requirement may be easy to achieve when the "smart" system is first installed but can later lead to problems when an increasing use of the wireless channels reduces the reliability of the communication system. How many plumbers / heating engineers have equipment for evaluating radio channel occupancy when attempting to fault find on a "smart" system that has become unreliable.

 

[BlueLoo]

Only if such a system as zoning is a requirement.



That is simply not true is it? I would much rather attempt to explain to my partner how a to operate a TRV4, than how to set up and operate a fancy bluetooth wireless unit times and temperatures. I am well used to tech, but even I would expect to have to sit with the manual for an hour or two to understand them. Put it in front of my partner and her eyes would glaze over.

You don't "operate" TRVs. You set them and eave them alone. They have huge hysteresis and are no use at all in a dynamic thermal environment where the inhabitant wants different temps.
In fact, unless you are at the damn things many times a day, you can't really have a dynamic temperature profile in the rooms.

Smart TRVs are set globally via the app and can be boosted by simply pressing a button on the valve itself. Couldn't be simpler.

You have to think of the customer here. Don't taint them with your own luddite prejudices and if something isn't working well, it doesn't matter how simple or complex it is, it just isn't working and should be changed.