Sanity check plan new zone

pacatatucotianao

Hello All,
First time posting here, so let me know if I'm doing anything wrong regarding the forum rules/policies.

I recently moved into a house that has central heating only on the ground level. My plan is to also have heating upstairs. Luckily, the combi boiler (Vaillant Ecotec Plus from 2021) is already upstairs, so it should be fairly straightforward. I've now drafted up three plans for this but wanted a sanity check on them and some help choosing. They are:

First (traditional) Plan

1. Branch the flow immediately at the boiler and add two zone valves: One for the upstairs and the other for the downstairs.
   1. The one going downstairs would go into a simple manifold (no pump or thermostat) that is already there, and which branches off to the radiators downstairs.
   2. I would replicate the design in 1a for upstairs. That is, have the zone valve for upstairs lead into a simple manifold that would supply two radiators for the two rooms upstairs.
2. Connect the return immediately before the expansion vessel.

Advantages: Straightforward plan, fairly cheap, and I feel confident about doing it.

Concerns about first plan: I've heard very bad things about zone valves. They tend to break and need repair fairly often. This is a problem for me because I travel quite often, sometimes for around a full month. I wouldn't want my house running the heating full for a whole month because the zone valve has jammed.

Second Plan

1. As 1, but have the zone valves in the return portion of the circuit.
   1. Zone valves would connect back just before the expansion vessel.

Advantages: Same as those for the first plan.

Concerns about second plan: Same as those for the first plan

Third Plan

1. Branch off the flow portion and feed two more modern manifolds with thermostats: One for downstairs and another for upstairs.

Advantages: So far, I've not heard any issues about these new manifolds malfunctioning in the way traditional zone valves do. Also, I plan to add underfloor heating to the downstairs floor in the nearby future.

Concerns about third plan: I don't see this as a common suggestion for setting up different zones, so don't know if I'm missing something. Also, I have no idea about how to install these things, so would prob need to read up quite a bit on them. But if people say it's worth it, I would be happy to look into it.

Thanks for any help/suggestions you all can share!

EdTheHeaterMan

Sounds reasonable. I'm going to go deeper in to your plan to see if anything is off. are you located in UK?

hot_rod

sounds like you need to shop for a better brand of zone valves.😉

There is not a lot of difference between a zone valve and a zone actuator on a manifold. Often they are the exact same operator as one another

Zone valves with a short life span are often short cycling themselves to death

On the average a ZV cycles 5000 times a heating season. Quality valves, gear trains, motors and switches are designed for 100,000 cycles. Or 20 years of service.

EdTheHeaterMan

It appears that the internal pump of some of the Vaillant Ecotec boilers can handle multiple zones.  Vaillant boilers have not been sold in the USA for many years, so I'm not familiar with them. 

I just caution you that some of the Modulating Condensing combi boilers have internal circulating pumps that are only designed for small heating systems.   Those other manufacturers recommend primary secondary system design with separate system circulator pump and to only use the Boiler’s internal pump to sent the water from the boiler to the system loop

As far as Zone Valves, I have found that Califfi has a dependable valve and actuator that may be available to you. From my experience the Honeywell V8043 valves can have a useful life of over 10 years if they are not overworked by short cycling,  The Taco 570 series valves are also pretty bullet proof.  But I’m not sure they are available in UK

pacatatucotianao

Thanks for the replies so far!

Good to hear about the votes of confidence for zone valves. And thanks for the tips.

@

https://forum.heatinghelp.com/discussion/comment/1813248#Comment_1813248

Thanks for the attachment and for the info. I'll get in touch with Vaillant to ask about my specific model on this matter.

I'm located in the Netherlands, by the way.

I take it from the replies then that first and second plans are probably a better way to go?

EdTheHeaterMan

YES.   However the location of the Expansion Tank (the American for expansion vessel) is not clear on the Vaillant diagram.  This was a sales brochure and not a technical document.  The Location of your expansion tank is unclear  Would it be A or B

Also: how many radiators are on the lower floor existing zone

pacatatucotianao

Nice, thanks for the confirmation.

My expansion tank/vessel is in position B.

3 radiators in the ground floor. One large (~3.5kw) and two small ones (~1kw). Notably, there is also underfloor heating in the bathroom (~4 m2).