A blank piece of paper!

[dolph]

It has been a long time since you guys gave me invaluable help for me to create two bedrooms with ensuites for my twin young teenage lads. Time flies and now they are almost 30 (I’m retired) and have bought a duplex flat. Basically it was a tip, but having stripped it right down we are now ready to put it back together.

Electrics have been sorted with a great sparky, I have used the skills you taught me to enable us to build two bathrooms, one ensuite, and the kitchen is on order. However we are struggling to find a good central heating installer. We have had three round but they are only interested in providing bog standard systems, whereas we are looking for something a little bit more elaborate.

Let me explain it is situate on 2nd and 3rd level, on the first floor we have a large kitchen/diner that leads on to a reception room. Upstairs there are two bedrooms that have two bathrooms between them, as we divided one big bathroom into two. All the floors are concrete bison beams with high 8 feet ceilings. We propose creating a false ceiling throughout the first floor so that all piping can be attached to the original ceiling making installation more straightforward than normal.

The idea is that the common area will be the kitchen/diner. The other rooms will all be bedrooms so they can take in a lodger to help with the bills! Typically they will treat their bedrooms as their main personal areas (foldaway beds on order).

We really are looking for a gas central heating system that will enable them to individually control their own room temperatures, do such controlled systems exist. There will be radiators, cant have underfloor, in 3 bedrooms, 1 in kitchen, small one in tiny hall and two small towel rails. In all around 22000 BTU/7000wts.

Blank paper, any ideas that I can put to a gas engineer. Probably looking towards a combi system, as both my boys work funny hours and it would be very unlikely that any of them all will need to shower at the same time, anyway there is no room for a cylinder, roof space belongs to landlord, no entrance allowed.

 

[23vc]

Zone control with combi boiler is pretty common I thought?
Although it may not be the best choice if multiple showers are required at the same time.

 

[Doggit]

I've never used them yet, but there are a lot of electronic thermostats like this, and they would just be an addition to any standard install. I think as 23vc suggests, the hot water supply may be a bit more of an issue, so you either need a high power combi boiler to handle 2 showers, or a system boiler with an unvented cylinder; but that needs a yearly chekup to make sure it stays safe.

You need to get a few more plumbers in, and maybe ask the neighbours for any recommendations.

 

[dilalio]

If you can deal with the worst case scenario and get occupants to stagger shower times then a combi will suffice... but it all depends on washing habits of the household.
Evohome for independent heating control.

 

[dolph]

Thanks guys as usual you have given me plenty of food for thought. I have followed up on your suggestions re electronic wi fi TVR and the EVO Honeywell seems to meet my criteria. One small question, would there be a need to put these EVO TVR's on every radiator, can understand bedrooms and kitchen/living room, but what about the tiny rad in the hall cant see the hall getting up to temperature as it is about 6 feet long and the stairs lead directly off it and the heat would "shoot" up there. How do the towel rads in the bathrooms get controlled will they need these EVO's. Finally do these Honeywell controls have to fitted by an "expert" or if I mention it to the plumber can he do it at the same time as he fits the system?

It would appear that my sons will hardly ever need to shower at the same time, well they wont as they will share the house bathroom, as the ensuite will be let out, they know that ensuited rooms command a premium rent in house shares, so they tell me!

The combi I was looking at gives 12.7 lpm @35degrees, this I understand gives a good shower. My own system put in many years ago, this is harking back to your great help you gave then, was on the advice of I think Bahco powered by a pump basically as the original gravity system for the shower would not work as the two new bedrooms were so far away from the cylinder. It was only a very cheap variable pressure "showermate" that I kept down to one bar, but not only did it give a decent enough shower for the boys, at school then, but also they often showered at the same time and it worked beautifully. Lasted well over 10 years and changed it for a 1.5 bar Salamander last year.

I did the bucket test today in our main bedroom ensuite where the shower spray reaches from one end of the 1700 bath to the other. It came out at 7 lpm so am I missing something here. The combi is 12.7 lpm, halved 6.35 lpm (10% less than mine) which I believe would not be a power shower but would be acceptable. Is there something else I am not taking into consideration as whilst they probably wont "shower conflict" it would be comforting to know that the rare occasions they might they will at least come out clean.

As always everyone many thanks for your replies. Whilst I cant do it myself anymore it does help when I am talking to the different tradesmen.

 

[muggles]

@dolph another way of doing it, depending on what stage you've got to, would be to have a wired system which eliminates any potential communication issues associated with wireless systems. Radiators can be run off a centralised manifold, or each radiator can have an electric actuator on it connected to a thermostat which turns it on and off as required. You can then have programmable room thermostats in each room which can individually fire the boiler according to who needs it on when.

If you do go for Evohome, it can do the above but yes you do need to have an Evohome TRV (not TVR, that's a car...) on every radiator. If you don't, the radiators without Evohome TRVs will come on every time a radiator with an EH TRV calls for heat. The EH system really does need to be fitted by someone who is familiar with it, as it is far easier to make a total pigs ear of it than it is to get it right.

As for boilers, with this kind of system and your total expected load, the only sensible option is a Viessmann 200W. Everything else on the market will cycle more than Chris Froome, leading to increased wear and tear and higher gas bills. The Viessmann has a minimum output of just 1.8kW which is perfect for small properties or properties with fully zoned systems.

 

[Doggit]

If you don't, the radiators without Evohome TRVs will come on every time a radiator with an EH TRV calls for heat

The caveat to this, would be to ask what the main heating criteria would be. We could assume that the house would always be heated at certain times of the day, and that some rooms wouldn't be, so the eTRVs would be removing the heat from that room, but it would still be required elsewhere, so the hallway and bathroom etc could actually have standard TRVs.

To require an eTRV on every rad, would be to assume that just the bedrooms in question would need heating, and the rest of the house could stay cold. Beyond that query, I'd go along with erything you've said.

 

[dolph]

Thanks guys, your answers had me diving into research, you can when you are retired, to try and understand them more fully. I like the idea of the centralised manifold as I forgot to mention in my initial posting that between the two bathrooms is a small utility room (to put washing machine/Dryer in) but it would also be a great place for the manifold to be situated.

As the piping to the radiators would be in one piece ie no joints I was thinking plastic would be perfect as the only connections would be above "ground". This is something I could do myself very easily, especially as I could pressure test the flow and return "circuits" after the manifold using mains water supply pressure.

Also if we used the wired system does this mean at the manifold, electric activators would be fitted thereon, I have discovered now these exist for underfloor heating but are they available for radiator systems? Again if so I can easily chase out the appropriate walls and run the wires needed from thermostats to manaifold. I take it a continuation of these wires would go to the boiler via circuit board and/or relay to fire up the boiler, again a simple job before the downstairs ceiling is reconstructed.

Now looking at the small hall radiator, yes it would always be on when any of the TRV's (point taken Muggles, We want comfortable heat not uncomfortable car!)but on reflection this would probably be a good thing. If someone is in residence then a small amount of heat would permeate from the hall heating also the upstairs area at top of stairs, a normal TRV could restrict if necessary. Small question, as the hall will be within 5 feet of the boiler could say a 10mm spur be made off the 22mm flow and return pipes to the manifold be used?

As regards towel rads in the bathrooms could these be connected like this:-

1/ could the 15mm piping from the manifold to the ensuite bedroom be spurred off in say 10mm pipe to the towel radiator, as the only time that bathroom would be used is when the ensuite is occupied, it also happens to be the smallest room/radiator (3500btu/ towel 500btu)

2/ similarly the main bathroom could be branched off the kitchen radiator piping (3800btu/towel 500btu)

The distance to the two towel rads would be no more than 1.5 metres as they will back on to the utility room walls, as such and as the towell rads are very small would 10mm suffice?

Finally a silly little query, what calculator do you professionals use to work out radiator btu's/watts. I have used betterheating/plumbnation/victoria plumbing and with exactly the same info the results are completely different eg reception room 2400 to 4300, kitchen 1870 to 3400.

Again many thanks for taking the time to reply I do continue to appreciate it and it will help so much when I give the plumber the full specs for the job required.