The abandoned bathroom project is looming on the horizon after about 15
years of remaining a stripped out cave so I'm addressing the heating
dilema...

The house refurb started off with a 4 zone UFH manifold serving the
upstairs living areas; downstairs bedrooms remained unheated for many
years but were then furnished with room radiators on a t/stat zone valve
from boiler feed. All good and working perfectly so far...

5 years ago we had a new "upstairs" extension added to the living area
giving 3 more rooms (4 zones) so I fitted a 2nd UFH pump/manifold from
the handy flow/return loop I'd originally left in the garage (now gym)
as a "just in case" and plumbed up the new rooms with in-screed UFH, all
systems still working magnificently.

I now have the downstairs bathroom left to sort out.
The room is underground as the house is built into a hill so floor slab
is 1970 un-insulated concrete on clay but it didn't ever have a cold
problem but ideally I'd like to UFH it. The obvious way would be a
single zone UFH manifold/pump but I'm running out of space in the airing
cupboard although I could squeeze one in but I'm thinking I could simply
use the return flow from radiators/UFH etc to do a few laps of the
bathroom before going back to the boiler, possible isolating it with a
zone valve on a bathroom t/stat.

Boiler has a max flow temp of 55 degrees controlled by weather
compensation and return flow is around 5 to 10 degrees lower.

So... Could there be a problem fitting a 3rd pumped manifold onto the
system (4 pumps including boiler pump) I've already plumbed up a
flow/return spur into the bathroom for a towel rail so not getting
"enough" heat from the floor isn't an issue but loading the boiler pump
up with another 20m of pipe could be? My logic is that as existing
manifold pumps are doing the lions share of overcoming pipe resistance
the boiler pump is only serving 5 radiators and a towel rail (in the
upstairs shower room) and the loop to 2nd ufh manifold so it's not
excessively loaded.

Any obvious pros/cons I might have overlooked?

Cheers
Pete

On 27/07/2020 11:04, www.GymRatZ.co.uk wrote:
The abandoned bathroom project is looming on the horizon after about 15
years of remaining a stripped out cave so I'm addressing the heating
dilema...

The house refurb started off with a 4 zone UFH manifold serving the
upstairs living areas; downstairs bedrooms remained unheated for many
years but were then furnished with room radiators on a t/stat zone valve
from boiler feed. All good and working perfectly so far...

5 years ago we had a new "upstairs" extension added to the living area
giving 3 more rooms (4 zones) so I fitted a 2nd UFH pump/manifold from
the handy flow/return loop I'd originally left in the garage (now gym)
as a "just in case" and plumbed up the new rooms with in-screed UFH, all
systems still working magnificently.

I now have the downstairs bathroom left to sort out.
The room is underground as the house is built into a hill so floor slab
is 1970 un-insulated concrete on clay but it didn't ever have a cold
problem but ideally I'd like to UFH it. The obvious way would be a
single zone UFH manifold/pump but I'm running out of space in the airing
cupboard although I could squeeze one in but I'm thinking I could simply
use the return flow from radiators/UFH etc to do a few laps of the
bathroom before going back to the boiler, possible isolating it with a
zone valve on a bathroom t/stat.

Boiler has a max flow temp of 55 degrees controlled by weather
compensation and return flow is around 5 to 10 degrees lower.

So... Could there be a problem fitting a 3rd pumped manifold onto the
system (4 pumps including boiler pump) I've already plumbed up a
flow/return spur into the bathroom for a towel rail so not getting
"enough" heat from the floor isn't an issue but loading the boiler pump
up with another 20m of pipe could be? My logic is that as existing
manifold pumps are doing the lions share of overcoming pipe resistance
the boiler pump is only serving 5 radiators and a towel rail (in the
upstairs shower room) and the loop to 2nd ufh manifold so it's not
excessively loaded.

Any obvious pros/cons I might have overlooked?

Cheers
Pete


I'm not sure how you propose to control the temperature in the bathroom.
If the flow is in series with the other zones, you can't turn it off
without affecting those - unless you have some sort of by-pass. Also, if
none of the other zones is calling for heat, the bathroom won't get
heated even if it needs it.

Adding another zone shouldn't be a problem. The boiler pump only has to
keep each zone supplied through relatively low resistance piping - the
zone pumps do all the work. Why does the zone pump and mixer valve need
to be in the airing cupboard? Surely it can be local to the bathroom?
All you need in the airing cupboard is the zone valve.

Unless you're going to dig up the floor, you'll need to raise the floor
level by at least 6" by the time you have installed an insulating slab
under the heating pipes and screed above it. Is that a problem?
--
Cheers,
Roger

On 27/07/2020 14:48, Roger Mills wrote:
On 27/07/2020 11:04, www.GymRatZ.co.uk wrote:


I'm not sure how you propose to control the temperature in the bathroom.
If the flow is in series with the other zones, you can't turn it off
without affecting those - unless you have some sort of by-pass. Also, if
none of the other zones is calling for heat, the bathroom won't get
heated even if it needs it.

Adding another zone shouldn't be a problem. The boiler pump only has to
keep each zone supplied through relatively low resistance piping - the
zone pumps do all the work. Why does the zone pump and mixer valve need
to be in the airing cupboard? Surely it can be local to the bathroom?
All you need in the airing cupboard is the zone valve.

Unless you're going to dig up the floor, you'll need to raise the floor
level by at least 6" by the time you have installed an insulating slab
under the heating pipes and screed above it. Is that a problem?

Thanks Roger.
I was thinking of having it on the C/H return with a 3-way zone valve so
when call for heat is on, return is diverted through bathroom switching
to simple bypass back to boiler when demand is satisfied.

The second UFH manifold doesn't have an easy cabling route back to the
boiler so I have the upstairs shower room/old hall zone set to be on
longest and a degree C higher then the other zones so the boilers always
got a call for heat if the new zones also need it. Nothing ever
overheats as weather compensation modulates boiler temp perfectly. I was
going to cable it back if required but as it stands my work-around means
I've not needed to.

Being upsidedown the airing cupboard is downstairs with existing
manifold flowing upwards into the upstairs UFH zones. The boiler is in
the room on the left of (adjoining) the airing cupboard and the bathroom
is directly adjacent to airing cupboard across the hall. I've already
channelled out an access route into bathroom across the hallway floor
through the screed and the 4" screed that was in the bathroom on top of
the slab has already been removed.

The dismantling of the original downstairs heating and bathroom was
because all the original copper pipes were set into the downstairs
screed when the house was built in the early 70's so copper pipes had
corroded and leaking into floors and walls.

In the new extension upstairs the builders did slab on insulation so I
had to use a 3mm (ish) multi-foil to separate egg-box UFH pipe tray and
floor screed from slab. This along with the air-spaces on the underside
of the egg-box seems to give plenty of thermal resistance between screed
and slab so I reckon I can get away without any additional insulation
(other than a multi-foil) downstairs as the floor slab is 4" below the
hall height so I'm tight on space but using a multi-foil the screed will
still be 4" deep between the pipe retaining castellations of the tray.

If all that makes sense.
Another reason for using C/H return is to suck a bit more heat from the
return to aid condensing.

It's actually a lot simpler than it sounds although anyone coming in
blind might struggle to work it out.

Cheers - Pete