System advice

[b21playa]

Hi all

Hope everyone is well!

I need some help as getting conflicting advice from some heating engineers I’ve had around to quote.

I currently have a gravity fed system which when we moved in a couple of years ago was on a W plan, which I immediately had changed to a S+ plan. Current boiler is a Valiant ecotec plus 438, set at part load as it cycles a lot. Not not if boiler is 100% right. We are planning renovations for next year and want to move the boiler as well as upgrade to an unvented cylinder (new water mains needed as well). The house has 3 floors and will end up with 21-23 radiators in total, some large ones but also some smaller ones. Currently pipework comes off valves at 22mm and then predominantly 15mm runs everywhere.

Now I’ve had a few heating guys over and I’ve been told my current boiler size is fine @ 38kw but also some state an 18kw one would suffice as well. They all said to put new runs of 22mm in and drop down to 15mm for each radiator.

Can anyone help with advice/suggestions. I’m a bit stuck as to what is correct, changing the boiler isn’t an issue if it needs it.

Thanks in advance

 

[sxturbo]

Do a home heatloss calculator, that will tell you what size boiler you need.

I'd prob say a 24kw would be the size to go for, but need to do proper calc. I'd also say a hot water priority with a proper smart heating system, with opentherm if you can. Put in oversized rads and have low temp economical and environmental friendly heating. You'd have to find an installer that knows about this sort of thing though and isn't just a boiler slinger

 

[CBW]

21 - 23 radiators, must be a large house? I know you said 3 storeys, but I’m guessing lots of rooms? You’ll need to work out the Kw rating of each radiator, the kw rating needed for the unvented cylinder and that should give you some sort of idea, and what Sx has said about heat loss.

 

[BlueLoo]

Talk to the installer about manifolding the floors if you do install new pipework. Better in most ways. Especially on large networks.

 

[DP]

While cannot say what follows is an issue with current series 4 Vaillants, these boilers needed good planning otherwise boiler would shut down for circulation issues. CBW might be able to shed more light on that

You may want to zone the floors if plumbing is to be altered. If not Evohome would do this for you. 438 seems to be a lot of power for domestic dwelling unless the house is a mansion with high ceilings and rooms like tennis courts

 

[BlueLoo]

While cannot say what follows is an issue with current series 4 Vaillants, these boilers needed good planning otherwise boiler would shut down for circulation issues. CBW might be able to shed more light on that

You may want to zone the floors if plumbing is to be altered. If not Evohome would do this for you. 438 seems to be a lot of power for domestic dwelling unless the house is a mansion with high ceilings and rooms like tennis courts

I can highly recommend using smart tech to do the zoning rather than relying on cumbersome 80's single, double zone design. Works great and less to go wrong

 

[b21playa]

Do a home heatloss calculator, that will tell you what size boiler you need.

I'd prob say a 24kw would be the size to go for, but need to do proper calc. I'd also say a hot water priority with a proper smart heating system, with opentherm if you can. Put in oversized rads and have low temp economical and environmental friendly heating. You'd have to find an installer that knows about this sort of thing though and isn't just a boiler slinger

Thanks. At the moment we are running Hive

 

[b21playa]

21 - 23 radiators, must be a large house? I know you said 3 storeys, but I’m guessing lots of rooms? You’ll need to work out the Kw rating of each radiator, the kw rating needed for the unvented cylinder and that should give you some sort of idea, and what Sx has said about heat loss.

Yea lots of rooms and multiple rads in a couple of rooms

 

[b21playa]

Talk to the installer about manifolding the floors if you do install new pipework. Better in most ways. Especially on large networks.

When we changed to S plan, we separated upstairs and downstairs heating so run 3 zone valves all connected to Hive

 

[b21playa]

While cannot say what follows is an issue with current series 4 Vaillants, these boilers needed good planning otherwise boiler would shut down for circulation issues. CBW might be able to shed more light on that

You may want to zone the floors if plumbing is to be altered. If not Evohome would do this for you. 438 seems to be a lot of power for domestic dwelling unless the house is a mansion with high ceilings and rooms like tennis courts

Currently zoned; downstairs separate and then 2 top floors. House isn’t a mansion my any means, but not your bogo house either. Ceilings are 2.7m

 

[BlueLoo]

When we changed to S plan, we separated upstairs and downstairs heating so run 3 zone valves all connected to Hive

If you are redoing, seriously considering deleting the zone valve approach. Make every rad its own zone with smart rad valves.
With manifolding, it works really well in my setup. (I installed Wiser and removed the zone valves).

 

[b21playa]

If you are redoing, seriously considering deleting the zone valve approach. Make every rad its own zone with smart rad valves.
With manifolding, it works really well in my setup. (I installed Wiser and removed the zone valves).

I was considering moving to smart valves instead of zone valves. I guess I will still need a zone valve for the tank and one for the actual heating side. I need to look at costs as 23 smart valves is nearly £1400 by themselves

can I ask what manifolding is, so I know to ask the installer about it.

thanks

 

[BlueLoo]

I was considering moving to smart valves instead of zone valves. I guess I will still need a zone valve for the tank and one for the actual heating side. I need to look at costs as 23 smart valves is nearly £1400 by themselves

can I ask what manifolding is, so I know to ask the installer about it.

thanks

You'll only need one zone valve for the tank.

This will mean you only need a simpler hw+ch controller and much less wiring.

Do a full costing. Yes the valves are not cheap, but the plumbing and wiring and valving may even itself out

Manifolding is the modern (well 2000's+) way of process distribution.

Instead of having 2 pipes (feed & return) chasing the radiators around the house, you supply and feed to manifolds and then each rad has its own supply feed. This means that within reason, the system is naturally balanced. The pressure drops are the same to each rad and the pressure in the system is much more consistent.

Normally there is a manifold for each floor.

It's also a easier and cheaper way to do the plumbing.

https://coveredbridgeprofessionalhomeinspections.com/blog/?attachment_id=3700

 

[b21playa]

You'll only need one zone valve for the tank.

This will mean you only need a simpler hw+ch controller and much less wiring.

Do a full costing. Yes the valves are not cheap, but the plumbing and wiring and valving may even itself out

Manifolding is the modern (well 2000's+) way of process distribution.

Instead of having 2 pipes (feed & return) chasing the radiators around the house, you supply and feed to manifolds and then each rad has its own supply feed. This means that within reason, the system is naturally balanced. The pressure drops are the same to each rad and the pressure in the system is much more consistent.

Normally there is a manifold for each floor.

It's also a easier and cheaper way to do the plumbing.

https://coveredbridgeprofessionalhomeinspections.com/blog/?attachment_id=3700

That sort of makes sense, just how would the heating not come on when the hw is called?

I think I have some space for a manifold on each floor, the problem would be running so many pipes around the house in timber floors. I assume main feed and return to manifold in 22mm and each radiator comes off in 15mm?

can 2 or more radiators come off a zone on the manifold?

 

[b21playa]

Also doing a search I can only find underfloor manifolds, but decided against underfloor heating due to costs