Is boiler underspec?

[harrythefurrysquid]

I used that one successfully with a WB Greenstar 30i, together with Drayton Wiser.

However I've seen a couple of people try it recently and say that it didn't work for them with WB boilers of a similar age, and I've also heard people saying it doesn't work with the latest WB boilers. So I'm thinking I got somewhat lucky.

 

[Mottie]

I've got a 4 bed house 11 rads and the 18kw boiler is fine.

We have a 3 bed 10 rad house with an 18kw boiler range rated to 14kw with a flow temperature of 62°. Works fine for us. I have the hot water on 24/7.

 

[polesapart]

Most new thermostats use TPI or similar algorithm.

The study into the effectiveness of these thermostats showed they actually increased energy use. And it concluded that it was probably because most people didn't understand how they worked.

A link to the study, please? (Apols if already posted in the thread)


I certainly have customers who struggle with their controls

 

[Harry Bloomfield]

opentherm adaptors for the Bosch boilers like there are with vaillant

The Vaillant adaptor is the VR 33, which is not available for the UK market. It was intended for the EU market, but even so is difficult to source in the EU.

 

[FiremanT]

Later in the thread, the OP explains that they had no choice in the matter, and the boiler was sized and specified as part of the grant assessment.

Fair enough, I wasn’t going to plough through 5 pages.
But he had THREE quotes, the other two specking bigger boilers

 

[bruba]

An update... Boiler was set to 65C Heatlink was relocated in an easier place for me to access (not in the loft).

Engineer tested the flow output/return of the radiators (63C) and they were aligned to the boiler output 65C.

Temp on the Nest thermostat display did not get past 19C even after 3 hours of continuous use.

It also took about 90 mins to get from 12-14C to 19C which they advised me was normal.

 

[Johntheo5]

3 hours continuous use doesn't mean that the boiler was running at 18kw output, it should have been running at 65C, if it wasn't then its under powered for the heating load, if it was running at 65C then I would go and measure the gas consumption for say exactly 3 minutes, you will then be able to calculate its exact output.

 

[JonathanM]

Have you a link to that study please?

A link to the study, please?

@vulcancontinental @polesapart Study link at end of post

@sxturbo, I’ve tagged you because I replied to you earlier and gave some dubious information.

Sorry for the delay. Previously I had only read an article where the study was discussed, not the study itself. I’ve been checking my bookmarks, but can’t find it again. The thrust of the article was that the thermostats only spent a tiny amount of time under TPI control, because people didn’t use them properly, and that there was a small rise overall in the amount of energy used by the heating system.

I think I’ve found the actual study now, but it’s not quite as clear cut. Also, it’s an old study, so you’ve probably seen it before. I don’t think I will be repeating this claim again, unless I understand it a bit better. It definitely says TPI was only in operation for about 9% of the time. As regards cost, at 9.1 it seems to be saying that TPI had no effect on gas consumption, then at 9.2 I think it is saying there is a tiny increase in the electricity used by the boiler. It doesn’t really seem to reach any firm conclusions about the benefits, or not, of TPI, apart from it’s too complicated to assess accurately.

FWIW, my own recent experience of helping my uncle with his new TPI thermostats, is that they can be very confusing. He has always been interested in boilers and controls, but he found it very hard to understand why the new thermostats click off well below the set temperature, and he still hasn't got them running like he wants. He does have a very complex set up, though.

https://assets.publishing.service.g...t_data/file/47962/1149-condensing-boilers.pdf

The results of this trial have highlighted the complexity of achieving energy efficiency savings from improvements to boiler operating systems and how an innovative technical intervention cannot solely compensate for external factors with a potentially more significant influence over the heating system efficiency such as the thermal performance of the building and the occupant’s behaviour. The efficiency of a heating system is dependent on a myriad of factors, some that can be remedied through technical developments and structural works, and others that are dependent on the less tangible factors relating to human behaviour.

 

[bruba]

3 hours continuous use doesn't mean that the boiler was running at 18kw output, it should have been running at 65C, if it wasn't then its under powered for the heating load, if it was running at 65C then I would go and measure the gas consumption for say exactly 3 minutes, you will then be able to calculate its exact output.

They used some equipment to test the output on the radiators and it was around the 60-65C mark. So that means the boiler is running at 65C?

In which case I can measure the gas consumption for 3 minutes. Not done this before but I am sure it is fairly straight forward.

Thanks

 

[Johntheo5]

Quite easy if you have a standard meter, post on a photo, read all the decimal places at the start and end of the 3 min period, use your phone/stopwatch, you should be looking at a consumption of ~ 0.077m3 assuming say 15kw boiler output at a efficiency of 88%.

 

[sxturbo]

If all the rads are at 65c then it would seem the boiler is not "under powered" as it is keeping the flow temps required of it.

As for the reason the house won't get warmer than 19 degrees I'm unsure

Is it the house won't go warmer than 19 or the nest won't call for heat above 19?

 

[sxturbo]

The Vaillant adaptor is the VR 33, which is not available for the UK market. It was intended for the EU market, but even so is difficult to source in the EU.

No they weren't intended for any other market than Netherlands as they have a specific requirements that all boilers operate with opentherm, I know many people was importing them and some had warranty refused by vaillant (or at least vaillant tried refusing)as they don't officially recognise the part in the UK.

Seems like there is a similar adaptor for Bosch boilers aswell now, also only available from Netherlands by looks of it.

 

[Johntheo5]

If all the rads are at 65c then it would seem the boiler is not "under powered" as it is keeping the flow temps required of it.

It could be running at any power output between its min and max outputs if the flowtemp is 65C dependant on the actual rad outputs, measuring the gas consumption will define this.