How can I make this boiler installation more efficient? System + tank on/off

[Matt723]

Hi All

New house, new boiler! The set-up is:
- Vaillant Ecotec Plus 637, system boiler single plan
- Tank elson zircon 250zi, no immersion
- Programmer Drayton LP722 (dual channel, heating and hot water)
- A Salus controller, not too sure what does is used for.

As you can see from the PCB photo, the eBus port are not connected. I am concerned that this is a simple on/off set-up with no modulation and poor efficiency. On top of this I cannot control the hot water temp on the boiler, I'm concerned this would heat at maximum temp unecessarily.

How would I go about making this as efficient as possible? I was thinking:
- Vaillant vSmart to control from the app (or any other smart controller that can modulate, Tado cannot with system boilers)
- Possibly combine with two smart radiator thermostat (two rooms upstairs don't need to be heated at night)
- an outside temp sensor for the boiler to modulate efficiently?

Any idea?
Many Thanks!

 

[Deleted member 281264]

Use Sensocomfort it's much better

Also unless you live in a huge mansion 37kw boiler is grossly oversized

 

[JohnD]

Where is your room thermostat?

Why are your pipes uninsulated?

On top of this I cannot control the hot water temp on the boiler

Do you mean the cylinder?

 

[ianmcd]

Vaillant Ecotec Plus 637, system boiler single plan

you have an S plan the S does not stand for single

 

[CBW]

As above - Vaillant ebus controller (thermostat). Grey cable should be heat resistant flex and you shouldn’t be removing the cover on that boiler. Also as above, insulate the pipes.

 

[monkeysballs]

insulate dhw pipes yes but not CH pipes unless they go outside the heated envelope of the building

 

[Harry Bloomfield]

- Vaillant vSmart to control from the app (or any other smart controller that can modulate, Tado cannot with system boilers)

A Vaillant control system will do all that.

- an outside temp sensor for the boiler to modulate efficiently?

Add a Vaillant sensor to the above. All very easy to install, especially the wireless versions.

 

[JohnD]

insulate dhw pipes yes but not CH pipes unless they go outside the heated envelope of the building

Assuming you want to deliver heat at random amounts and places, including unused rooms, storage areas, and voids under floors, instead of specifically into occupied rooms until they reach your desired temperature

 

[monkeysballs]

the heat isnt wasted as it heats your house, ive tried micro zoning it isnt worth it and actually costs more for me than letting the weather comp do its thing and heat 247

and voids under the floor i said to insulate those as i clearly said(unless they go outside the heated envelope of the building

and under a suspended ground floor is that, under a suspended first floor its effectively ufh

in a new build you are going to have sod all thermal mass internally so zoning hardly works as the heat will always migrate to where its colder

and unless your actually recommending them to rip all their walls and floors up to lag the pipes what are you hoping to achieve?

 

[JohnD]

So you've revised it to "don't insulate the ones you can't reach"

 

[Matt723]

Boiler size:
Thanks for pointing that out! It's a 2000sqft terraced, 5 beds 3 baths and there were 5 renters before. What is the implication of having 37 kw? Is there a risk of overconsuming energy? If that's the case I would definitely consider downsizing the boiler.

Thermostat:
Currently there is this in the corridor:

It's not connected to ebus so I'm concerned this is not efficient at all and just goes on (max power?!) / off..

You mention Vaillant SensoComfort being better but better than what? How does it compare to their vSmart controller (which I think is also ebus and can be controlled remotely via internet which we used in our previous place before when we had a Tado).

insulation:
Will get this sorted ASAP however sadly I can only insulate those I have access to. I fear the part underfloor between the boiler and the tank and the parts going uptsairs inside the wall are not insulated either

 

[Harry Bloomfield]

What is the implication of having 37 kw? Is there a risk of overconsuming energy? If that's the case I would definitely consider downsizing the boiler.

Over sizing means the boiler will short cycle - turn on and off with too much frequency, even when it modulates down to minimum. Such behaviour will cause extra wear on the boiler and waste gas.

 

[ericmark]

The boiler as you rightly point out is designed to slowly turn up and down to match the demand, this can be done using the return water temperature or the ebus, set up correctly likely very little difference, but using the TRV two methods, one electronic head links to a hub/wall thermostat and tells the hub/wall thermostat when the boiler is required. Or some careful balancing is required, so the wall thermostat turns on when heating is required.

I did the latter with mothers central heating, and I will admit it was not easy.

The TRV's will turn off the boiler, but there is nothing to tell the boiler when to restart, so there is some anti-cycle software which tries to adjust the restart time based on if the water returned hot last time it fired out within a set time, or similar, so if the whole house is warm, you want the by-pass valve to lift as all TRV's are closed, and hot water is returned quickly to the boiler.

The problem is there is no data as to how quick hot water must return, so what is unknown is what having radiators without a TRV will do to the anti-cycle software.

The next is where to mount the wall thermostat, the books say do not fit a TRV in room with wall thermostat, and put it in the slowest room to heat on the lower floor, with no doors to outside and not alternative heating, this includes sun through the windows, and in most homes there is no such room.

So I used the hall, which had a massive radiator to re-heat the hall after the front door has been opened, so the TRV on the hall radiator is set lower than the wall thermostat, so it can reheat fast to say 17ºC but then slows down before it hits the 19ºC set on the wall thermostat, ideally in the winter it will never switch off the wall thermostat, but as spring arrives it can switch off the boiler. So we want the hall to be kept cool, so when we do get a warm day the thermostat will switch off.

This also relies on the hall cooling faster than the rest of the house, or programming a lower temperature over night, rest of house will cool before the hall.

Lock shield valve setting are critical to stop over shooting, and although mechanical TRV's have a huge temperature range between starting to close and fully closed, so ideal to work with the wall thermostat, that means there is no timed change in temperature, and I like three temperatures cool over night, warmer in the day, and even warmer in the evening, one wants to ensure the heating is running when the programmable TRV settings change, so I would set wall thermostat 0.5ºC down an hour before change due, and back up on change to ensure boiler runs.

So if home at 5, dinner at 6, TV at 7 bed at 11 then at 4 it drops 0.5ºC, up again at 5 and at 5.15 again it drops again and up again at 6, and so on, so each room heats in sequence. It can be done, I did it, but it took a year to finely trim everything to as I wanted it.

My TRV shows depending on which make, in both cases I have target and current, so you adjust the lock shield valve so in winter current does not exceed target, an energenie one (second) got smashed, and has been replaced with a TPlink Kasa one, but as yet not used over a winter, so no idea how good, both need hubs, and both connect to the wifi. Neither connect to the Nest Gen 3 thermostat, the cheaper eQ-3 used blue tooth, will only connect to one phone at a time, but does not need hub, and can be set without the phone, the Kasa can also be manually set, but the energenie you need a PC or Phone and hub to set them. Once the lock shield is set the eQ-3 works well, but the price has jumped since we left EU, were £15 in 2019 now over £20 for bluetooth version, although non bluetooth seen at £18:50 does not sound much, but I have 14 TRV's 9 electronic.