Central heating control, any errors?

[JohnW2]

.... if using a bus saves so much energy compared with private car, why are they so expensive?

I rather suspect that if one compared the cost of having a car for only those journeys which could be undertaken by bus, then, for the great majority of people, the cost of using buses would be appreciably (maybe far) less then the effective costs of buying, insuring, taxing, fuelling and maintaining a car, even with bus prices as they are.

Kind Regards, John

 

[ericmark]

With 2 buses a day but not weekend and three trains a day but not Monday and Friday and even then a steep hill between station and house, and nearest taxi 12 miles away, the car is not a luxury, but essential, last house I could have lived without a car, bus every 1/2 hour, and roads one could cycle on in reasonable safety, but alas not here, so you need a car insured and taxed even when using public transport, I drive down to the station, not that I need a car to get to station, but I do need one to come back.

Did consider an electric bike, however new rules limit power to 250 watt, so still a hard push up the hill. At least with an electric bike I can ride up the majority of the hill.

I do have a bus pass so for me the bus is free, but told one comes pass my house, but never seen it. And to pop down the road for a bottle of milk and wait 3 hours for return bus may as well not run.

However the point is the figures given on energy saved just don't add up. Take this advert for a fluorescent tube it says Wattage: 20W / Equivalent Wattage: 100W output is 2000 lumen this fluorescent tube at 2900 lumen is 28W so it would seem the non LED equivalent wattage is more like 22W not 100W and clearly can't compare with tungsten as they would not work in the fitting.

Programmable thermostats claim savings on your energy bill. But they can’t prove it. They make you punch in every temperature change you want throughout the day, and usually you can only program 2 or 3 changes. It’s annoying and complicated – most people don’t even bother. So despite their claims, most programmed thermostats stay at the same temperature all day. And that wastes energy. Programming just doesn’t work. So Nest found a better way. And a whole new way: it learns.

Do you believe that? It claims 10 - 12% saving, I am sure it does save some energy, as it stops the boiler cycling, but I would say most of the saving is due to the TRV scheduling, very little is down to Nest.

 

[JohnW2]

With 2 buses a day but not weekend and three trains a day but not Monday and Friday and even then a steep hill between station and house, and nearest taxi 12 miles away, the car is not a luxury, but essential ...

Fair enough - and much the same is true here.

However, your comment/question to which I was responding was about the cost of bus travel - but, if buses are not available for the journeys you want/need to undertake, then the question of their cost is clearly moot. My point was that if bus travel were an option, and if one kept a car only to do the journeys that could have be done by bus, then buses would almost certainly be the cheaper option.

Kind Regards, John

 

[ericmark]

Where I use to live, there were reasonable bus services, from Asda to village centre was £2:30 by bus, and by Taxi £2:40 and to your door, clearly a problem with public transport price structure. Only reason I used a bus was it was free with bus pass, My house to mothers house on a push bike took 17 minutes, by bus fastest was one hour, depending on connection could take nearly 2 hours as no hand shaking with buses, so some times one stepped off one onto other, and some times had to wait.

I would catch bus to Chester as it went to City centre, and saved car parking fee, but smaller towns and villages not so good.

But the problem be it bus or central heating is items are taken in isolation, be it car parking fee, or cost of servicing and repair, items are not compared as used in the real world, so question with my central heating, do I really need a motorised valve? If I can switch down the TRV's do I need to have a motorised valve? The logic seems to say no, the TRV's do the same thing, and in the flat we have just 4 radiators so 4 x £15 = £60 and motorised valve is around £24 and needs to be fitted, however the motorised valve is hard wired and has micro switches built in, so even if 4 TRV heads are a better option in theory, in practice one can't auto control them and interlink them.

Theory is reasonable easy if any TRV report target over current boiler runs, otherwise boiler stops, it really does not matter if TRV head is wifi, bluetooth, or hard wired, it should be easy enough to have a hub which reads all the data and simply switches boiler off/on, in winter with in my case some 14 radiators one would always be asking for heat, so a modulating gas boiler would just modulated on return water temperature, and it would auto switch off in the summer. Practice is you can't buy a reasonably priced system to do it, so with OpenTherm boilers we use some very expensive hubs and valve heads if we want fully automatic, with non OpenTherm the only link to boiler bus is with that manufacturers unit, so with Bosch for example it is a single wall thermostat, but we are not heating one room, I am heating 13 rooms including toilets etc. Also in my case oil fired boiler so it does not really modulate so no point in OpenTherm anyway.

Following posts on this forum, the number of people who buy Nest, and have an Opentherm boiler, yet want to connect it to simple switch off/on seems rather high.

So in my case the TRV heads will turn off the central heating supply to rooms when not required, but they will not control boiler, so need Nest to switch boiler off/on, what I really want is for Nest to read the TRV heads, but what I have is the TRV heads read Nest so the TRV heads on house ground floor auto set to same as Nest which means there is no longer a need to have the radiators in the room with the thermostat without a TRV as they are linked, but I am still told you should not have one in the thermostat area.

Clearly time to set it all up is summer, ready for winter, but it does mean I am crossing fingers and hope it works, the hall is the traditional place for the wall thermostat, in my case hall in centre of the house, so yes good place, but son's house hall is on the outside of the house, so the thermostat is not really going to report when the 4 main rooms need heat, it seems to be all done because of tradition rather than any thought as to where is best in that house. The idea that thermostat should be in the room kept coolest, with no alternative form of heating and no outside doors on ground floor, seems great, but in my house that does not exist even with 13 rooms, be it patio doors or normal doors only rooms on entry floor without a door is shower room and utility room both have alternative heating either from shower or washing machine. And entry floor is only ground floor for two rooms and house built on a hill, so living room not ground floor.

 

[winston1]

With 2 buses a day but not weekend and three trains a day but not Monday and Friday and even then a steep hill between station and house, and nearest taxi 12 miles away, the car is not a luxury, but essential,

So what did people in your situation do 100 years ago?

 

[ericmark]

So what did people in your situation do 100 years ago?

100 years ago the train was run by Great Western and ran through the centre of Welshpool and connected to the main line, the house I live in was not built, and the village had it's own bank and other shops so no real need to leave the village, there was a milkman and breadman so most goods delivered to the house, and there was a strong Church which ensured the elderly were looked after, and Welshpool had a canal that actually connected to the network, there was a road bridge over the canal it had not at that time been cut into unconnected sections.

The arrival of the motorcar resulted in rail, road, and water public travel going into decline, to get people to move back, we need the old infrastructure, which includes buses and trains handshaking, the old VOSA actually fined the bus company that ran the interconnecting service to train station because they altered route slightly to cope with trains being late. They were told if their time table said they leave at 2:10 they must leave at 2:10 even when the train they are there to collect passengers from has not arrived.

I remember in Dolgellau the bus drivers Wrexham to Barmouth and Dolgellau to Aberystwyth had to wait for each other and physical shake hands to ensure passengers could swap buses, with 3 buses a day, missing a connection is rather serious, and can leave one stranded, I use to ferry my dad's car to my sisters house so Shotton to Tywyn some 70 miles or so, by car it took around 2 hours, by bus around 3.5 hours, it was not worth getting some one to pick me up, OK maybe run into or out of Wrexham, but whole picking up, dropping off, exercise was around 6 man hours using bus/train and 8 man hours (two men 4 hours each) using car, so bus made sense.

However my old house to Wrexham looking at 2 hours on bus, ½ hour with car, so even with free bus travel unlikely to spend 4 hours on a bus instead of 1 hour in car, plus waiting for bus to start with, I see the point is a bus detour through one village, but when it detours through eight villages the end to end travel time could be bettered by a canal barge at 4 MPH. The people would plan out the routes, I guess never travel by bus.

And when I worked I would start between 7 and 9 am and finish between 4 and 6 pm, having buses where first arrives after 9 am and last leaves before 4 pm reminds me of chocolate fire guards, we want to stop drinking and driving so should be able to catch bus at 10 pm, and catch one that arrives at 8:15 am to allow you to walk a little way to work, and not only the bus, but the company, if a factory is 15 minutes walk from bus stop, and first bus arrives at 8:50 am then start time should be 9:10 am not 9:00 am so workers can catch bus.

In the local Deeside industrial estate the factories came to an agreement to stagger their start times each 10 minutes apart so spreading car traffic over 2 hours, to reduce congestion, but this means it is impossible to have a bus service for workers, as so many start and finish times. Before in the days of the steel works, they had trailer buses where the articulated units would hitch up to trailers as shift change times, everything was integrated around times, so trains, buses, and coaches were timed so you could use multi-buses or trains today they simply don't work together.

 

[winston1]

Interesting reply. Thanks.

 

[SimonH2]

In my case the immersion heater could not be used to heat house, as there is no pump on the hot coil it is thermo syphon, so there is no way to get water to circulate.

It would be unusual to do it with the DHW cylinder, but in theory possible though it would need a coil fitted further up than the boiler coil is normally located.

As two selecting radiators so only some rooms heated, not sure how it will work, be it from a immersion heater or main boiler, my previous houses were not well insulated room to room, they were good at stopping heat leaving the house, but it was noted you could turn bedroom radiators completely off, but with down stairs set to 20°C it was hard to get a bedroom below 17°C of course if the room below was not heated then yes bedroom could get very cold.

Very true. As I think I've already (sort of) mentioned, no amount of fancy control is going to get around the laws of physics - but you can minimise the problems. Our house is very sub-optimal, but I'm working on it a bit at a time.

... but where the TRV turns off and boiler is still running what happens to the heat? With modulating boiler OK, but simple off/on it will cycle, is this really better than the old throttling back of the lock shield valve?

Well yes, the eTRVs really need to be linked to the boiler so they can turn it off when heat isn't needed. But I think you misunderstand what the lockshield is for - because it is NOT a "control" valve.
The purpose of the lockshield is to configure the flow rate through the rad when the control valve is open. Back in the days before any controls, they were used to balance the system so that (at least to a decent approximation) so that when the control valves were open, each room would be heated "about right". In those days, the design of the system (sizing of rads in particular) and balancing of the system was an important part of any heating system.
These days with TRVs being almost ubiquitous, failure to design and setup the system properly is largely masked - and so (to be polite) "less effort" is put into those tasks.
But it's still very important - a wide open lockshield, especially if combined with an over-sized rad, will result in the system being unstable. What will happen is: control valve (TRV) opens (even a small amount), rad fills quickly with hot water, by the time the room temperature is getting towards setpoint the rad is putting a lot of heat out, room temperature over-shoots, TRV closes, room eventually cools down and cycle repeats. I strongly suspect that the operation you described earlier, where your TRV head shuts down well before the room is up to temp and then lets the temperature rise more slowly, is largely an attempt to deal with poorly designed and/or setup systems - and lets face it, who would want to deal with the support calls of "your eTRV head is rubbish" when it's the system at fault

I wonder if these energy saving organisations really know? ... We have seen so many daft statements, energy saving bulb for example ...

Indeed, it's one of those things where the statements are perhaps a little dubious.

Some times it not down to economy, it's simply what one likes, and in the main returning to central heating it's more about ensuring rooms not too hot for comfort than what it costs, and having hot water at turn of tap, and not having to wait for hot water to arrive.

I agree. The ultimate in energy saving on heating is to not have it at all and buy a load of warm clothing Not really an acceptable proposition for most of us these days.

Programmable thermostats claim savings on your energy bill. But they can’t prove it. They make you punch in every temperature change you want throughout the day, and usually you can only program 2 or 3 changes. It’s annoying and complicated – most people don’t even bother. So despite their claims, most programmed thermostats stay at the same temperature all day. And that wastes energy. Programming just doesn’t work. So Nest found a better way. And a whole new way: it learns.

Do you believe that? It claims 10 - 12% saving, I am sure it does save some energy, as it stops the boiler cycling, but I would say most of the saving is due to the TRV scheduling, very little is down to Nest.

Here we see one of those "you need to read their assumptions and what they are comparing with. Most will assume a poorly controlled and poorly configured baseline - against which it is easy to show savings. But then, is such a baseline such a bad starting point ? One of the aims behind the OpenTRV project was to provide control for those (IME a significant majority) users who are incapable or unwilling to configure what they do have. I've met a lot of people for whom the simplest of time clocks is "rocket science" and a thermostat is something to be used as a switch (ie it's only ever on max or min).
Against that, a Nest is pretty well guaranteed to be an improvement - but it's not going to achieve the results that room-by-room control could do.

... so question with my central heating, do I really need a motorised valve? If I can switch down the TRV's do I need to have a motorised valve? The logic seems to say no, the TRV's do the same thing, and in the flat we have just 4 radiators so 4 x £15 = £60 and motorised valve is around £24 and needs to be fitted, however the motorised valve is hard wired and has micro switches built in, so even if 4 TRV heads are a better option in theory, in practice one can't auto control them and interlink them.

You've answered your own question there. IF you can put a TRV on each rad AND link at least some of them back to working the boiler, then yes - you can dispense with the zoning (motorised) valve because you are now splitting the system into a zone per room. If you are relying on a wall stat operating a zoning valve, then you are not getting the full benefit of individual room control.

Theory is reasonable easy if any TRV report target over current boiler runs, otherwise boiler stops, it really does not matter if TRV head is wifi, bluetooth, or hard wired, it should be easy enough to have a hub which reads all the data and simply switches boiler off/on

Yes, it should be easy to do - but you have to remember that not one manufacturer wants an open and interoperable ecosystem - other than one based on their system.

, in winter with in my case some 14 radiators one would always be asking for heat, so a modulating gas boiler would just modulated on return water temperature, and it would auto switch off in the summer. Practice is you can't buy a reasonably priced system to do it

So you end up having to BIY it to some extent

 

[ericmark]

Well yes, the eTRVs really need to be linked to the boiler so they can turn it off when heat isn't needed. But I think you misunderstand what the lockshield is for - because it is NOT a "control" valve.
The purpose of the lockshield is to configure the flow rate through the rad when the control valve is open. Back in the days before any controls, they were used to balance the system so that (at least to a decent approximation) so that when the control valves were open, each room would be heated "about right". In those days, the design of the system (sizing of rads in particular) and balancing of the system was an important part of any heating system.
These days with TRVs being almost ubiquitous, failure to design and setup the system properly is largely masked - and so (to be polite) "less effort" is put into those tasks.
But it's still very important - a wide open lockshield, especially if combined with an over-sized rad, will result in the system being unstable. What will happen is: control valve (TRV) opens (even a small amount), rad fills quickly with hot water, by the time the room temperature is getting towards setpoint the rad is putting a lot of heat out, room temperature over-shoots, TRV closes, room eventually cools down and cycle repeats. I strongly suspect that the operation you described earlier, where your TRV head shuts down well before the room is up to temp and then lets the temperature rise more slowly, is largely an attempt to deal with poorly designed and/or setup systems - and lets face it, who would want to deal with the support calls of "your eTRV head is rubbish" when it's the system at fault

I think you have said it all there, last house was a problem, as all TRV's fitted to return, so radiators would get stinking hot before the TRV closed, so slowly bit by bit I closed the lock shield until the room was at set temperature, at which point not sure it needed a TRV fitted, OK the TRV did compensate for sun on the bay window, but had the original TRV head shown the temperature in degs C then would not have needed electronic heads, once I could set head to 19°C I knew if room was at 21°C then lock shield needed closing a little, but with head set to 3.5 not a clue when room at 21°C if lock shield or TRV needed adjusting.

But TRV head at moment set to 16°C they follow Nest and that is temperature set on Nest as don't want heating to come on, so all TRV's should be fully closed, except when programmed to exercise. Yet I hear the motors adjusting every so often.