New System Install

[kimber.kimber]

Hello All,

We've not long bought a 1920's detatched house which is in need of a complete replumb. In an effort to make the system as efficient as possible, we want to fit an Evohome system. The property will have multiple bathrooms in the future, so we are going to have a system boiler and pressurised tank.

As we are ripping the hole system out, I want to install it right, including taking advantage of the OpenTherm capability of the Evohome. Based on this, what would the ideal installation be for the pipe system, and what would the recommendations be for boilers? I've read about the current issues with intergas, but I know they have a great reputation for reliability etc.

So, I'm in you hands! Thoughts? I'm not a plumber, so you may have to go easy with me on some of the terminology!

Cheers in advance,

Ian

[kimber.kimber]

All,

Some more information to show that I have at least considered some points! Post above was written in haste at lunchtime!

We plan on utilising as many zones as possible, set as follows;
1) Lounge
2) Kitchen and utility
3) Dining room
4) Study
5) Hall, downstairs toilet & landing
6) Master bedroom
7) 2nd bedroom
8) 3rd Bedroom
9) 4th Bedroom
10) 5th Bedroom
11) Bathroom and toilet

With regards to the Evohome set up, I've used the configuration tool and think I need the following;
Evohome wifi base pack
Evohome hot water kit
14 TRVs
OpenTherm bridge

With regards to the boiler, I think I am leaning towards a Viessman Vitodens 100, with matching cylinder. I may make the cylinder dual coil to package protect for future solar upgrading.

My thoughts are as follows. The boiler allows plumbing as a 4 pipe system. I believe this does away with the need for the DWH valve? Is this correct? I know I need to get the hot water demand box for the boiler.

Due to the size of the property i think it should be plumbed with 2 zones. However, I think I can get away without installing the zoning valves, if I am using the HR92s? If I have to install them, they should be set to full open, to allow the TRVs to do their job properly?

Am I best having one rad without a HR92? E.g. The bathroom (towel rail only in here) or the toilet... I know in a traditional radiator set up, you normally have one without to allow the thermostat to do it's job.

I take it with the OpenTherm control, I don't need to have the weather sensor wired into the boiler?

What's people's thoughts on the boiler choice? I'm mainly choosing it due to the current issues with intergas, and the benefits of using their boiler with their cylinder. Would I be better spacing a Valliant ecotec, and buying the OpenTherm board?

Finally does anyone know the difference between the Vitodens 200 and 100? I've tried working it out, but currently I can only see that it might be the size.

Thanks again,

Ian

[Richard]

Hi Ian,

Well I am gonna be a little bias towards Intergas, as they are a cracking boiler! They are built for a 20 year service life and have a 10 year warranty on ECO RF and 7 year warranty on the HRE. We will be selling them shortly under our new shop - The INTERGAS Shop (launching February 2017).

Yes there seems to be some sort of issue with multizoning and OpenTherm on them when using the OpenTherm Bridge (so I have read and been told), but as I haven't tried this yet personally I cannot comment to the extent this issue occurs. There seems to be some setting/values on the Intergas boiler that may not have been adjusted properly, so I need to look at this.

The 4 pipe system may not be compatible with evohome, as I believe this can only be controlled with Viessmann's own controls. I personally would use a 2 pipe system and do 'hot water priority' with a 3 port diverter valve when using OpenTherm.

I would leave a towel radiator open circuit when using OpenTherm too, as the boiler pump likes to run for long durations and saves the water going through an automatic bypass valve during this time.

The evohome system still works very well with TPI & the weather sensor (Hybrid TPI) and nothing wrong with using this (but I do appreciate it is not as refined).

I hope that helps.

Richard

[kimber.kimber]

Richard,

Many thanks for taking the time to reply.

I must admit I do like the warranty for the Intergas, but as the boiler will be in for many years, I want to ensure that I protect for the OpenTherm element. If the fix for the Intergas is a new circuit board/chipset, it could be an expensive fix to gain the full control.

That said I am wondering if I would be better off installing the system without OpenTherm to start with and maybe make the upgrade a bit further down the line. Sometimes too many new things can make everything a little tricky! This may actually lead me towards the Valliant, as I have heard their cylinders are very good too. If I don't have the OpenTherm in straight away, would the system layout be any different? i.e. the valving on the pipes? You'll have to excuse me, as I'm not 100% on the heating plan types.

What is the benefit of having the water going through a slave rad rather than an automatic bypass valve (other than warm towels?). I thought one of the major benefits with the evohome was to have the programmable TRVs on all rads?

Finally is it best to use TRV's everywhere, or should there be a wireless stat somewhere too? E.g. would I be better to run the hall on a wireless stat?

Thanks again,

Ian

[kimber.kimber]

Just to check I get this right. Systems can either be S Plan, S Plan +, Y plan or W plan.

S Plan has two, two port valves fitted, controlled separately. One for the rads, and one for the cylinder.

S Plan + is a variation of the above with multiple valves on the heating system to control different zones e.g. Upstairs and downstairs rads.

Y Plan has a 3 port 3 position valve that splits the flow between either the hot water or the central heating or both.

W Plan has a 3 port 2 position valve that split the flow between either the hot water or the central heating – i.e. giving hot water priority.

S Plan plus is pointless, as the HR92 and Evohome is doing the zoning for me?

If I set up as S Plan, I need two BDR91s, one for the water valve, one for the heating valve?

Can an S Plan be set up for hot water priority? Is the main advantage of this just heating the cylinder faster?

Why is setting up as a W Plan with a 3 way valve better than converting an S Plan with the valve set to open (If I make a future switch to OpenTherm that is)? I thought with OpenTherm it was better to have the flow always going around the heating system?

Cheers, and apologies if I'm being thick. I just want to make sure I get it right from the start.

[Richard]

I will be honest, my consultancy at this level of detail is chargeable. I don't mind a little help, but if you want me to help with system design, explaining system spec, etc it is charged for just as it would be with any other heating system designer.

OpenTherm works differently to a TPI controlled system and therefore the system design needs to be different. If I had a gas boiler, OpenTherm would be fitted in my own house but having a Ground Source Heat Pump 'on/off' and TPI control off the buffer cylinder is the best my system can achieve.

As for the PCB on the Intergas, spares are cheap on these boilers vs Vaillant/Viessmann/Worcester and one of the reasons we will be selling them shortly. There is much less things to go wrong too verses the others with a no quibble warranty should the worst happen.

Thanks,

Richard

[kimber.kimber]

I will be honest, my consultancy at this level of detail is chargeable. I don't mind a little help, but if you want me to help with system design, explaining system spec, etc it is charged for just as it would be with any other heating system designer.

Richard, sorry for the delayed reply, works been a little mental! Apologies, didn't mean to cross the line with questions, completely understand your position. I've been trying to get in touch with some local installers, but they've not been getting back to me.

Anyway, think I'm set with what I'm going to go for. I'll be in touch within a couple of weeks to make a purchase.

Ian