Heating setup query...help !!

[j1mmy]

Hi all - getting various quotes and designs for the same house so completely confused.

I will try and explain as much as possible so that you can get a better idea of what we are trying to do in order to give some suggestions.

1. We have run a 32mm blue pipe from mains into boiler room.

2. I need to install a water softener for the heating / hot water - not sure which make do you have any idea ? obviously should not restrict flow to water storage else we will lose power at taps. Kinetico 2050c has been suggested ?

2. We have installed under floor heating system with 7 zones, stat per zone and own circulating pump. Total Power = 13KW. (circuit 1)

3. We would like to install a Telford Tempest Unvented Indirect Stainless Steel Tank with external expansion vessel. This has a 3KW immersion and 35KW coil. (circuit 2)

4. We have an independent towel radiator circuit which we will control separate from the heating i.e. in summer. Total Power = 2.8KW (circuit 3)

5. On 1st Floor there are 8 Rads. Total Power=10KW (circuit 4)

6. On 2nd Floor there are 3 Rads. Total Power = 3.5KW (circuit 5)

7. There is one shower room on ground floor, 1 wet room + 2 Bath rooms on 1st floor and on 2nd floor there is shower room. So 2 Baths + 3 Showers total.

The house is detached with cavity insulated walls and double glazing. There is a large area of flat roof to ground floor approx 90sqm. The roofs in all floors are insulated.

All 5 circuits planned to be run from boiler(s) via a custom built low loss header ( this is suggested by 1 plumber ??). Each circuit will have its own pump. 3 x 15/50s for circuits 1 / 2 / 3 and 2 x 15/60s for circuits 4 / 5.

Bronze Pump to be installed on secondary return for hot water. This will be on its own timer.

Both Heating Circuits to have their individual stat / timers

Hot Water Tank to share timer control with Towel Radiator circuit.

There is a good possibility of 2 or 3 showers running at the same time.

Total House calculation comes in at around 30kw ( allowing 2kw for tank).

My main question is does this setup sound right / good ?

Some say 1 big boiler others say 2 small. What boiler or boilers would you recommend for this setup. Ideally I would like just the 1 boiler (Worcester 40cdi) as think having 2 just means 2 lots of bits that can go wrong. Worst come to worst the tank still has immersion so if boiler packed up we would still have hot water so not that fussed about backup. What water softener would you recommend ?

Is a low loss header recommended for this setup ? would I need a shunt pump ? how would the setup work to get the most condensing out of the boiler(s). I assume the HW needs flow 85deg, rads towel + normal need 75deg and UFH needs 40deg.

Another guy said no low loss header and ditch all the smaller pumps for a 25/55 pump for all the rad + UFH and one 15/50 for the HW.

Would really, really appreciate if you can look through this and give me some advice. I have tried to explain best as possible and really want this to work hence why asking for advice.

I have also attached a drawing of the system ( apols for the rough lines etc )

Jim

Untitled

• j1mmy
• 1 Oct 2011
• 1

 

[Biggles..]

Vaillant Eco tec plus 46 or 65 with Vaillant low loss. Shunt pump between boiler and LLH.(kw depend on cyl size and frequency of water usage)
Fit mixing valves to any heating circuit,ct for hot water.
Probably ditch the smaller pumps for a single circulator ( not sure why you've got 2 x 15/60's as that'd over kill).
Probably ditch the ufh pump as well if supplying as VT.

I'd use vaillants own controls for this.

Bit like this.

View media item 18024

 

[j1mmy]

Thanks for the reply.

So just to clarify...

Shunt pump between boiler and LLH ( what happens to pump inside boiler ?) and what spec should this shunt pipe be 15/50 ?

Fitting mixing valves to the heating circuits i.e setup towel and rad circuits @ 65 deg.

The UFH circuit has its own mixing valve as part of the manifold system. There is a 22mm flow pipe around 16m from the boiler so would it be fine to feed it full temp flow or fit an additional mixing valve near the LLH.

What is CT for hot water ?

Single circulator will replace how many of the smaller pumps - and does that mean this will mean less connections to the LLH and just zone valves depending on what circuit is calling.

What is VT in reference to ditching UFH pump ?

sorry for the questions.. just trying to get my head around this...

 

[Biggles..]

If the boiler contains a pump that is the shunt,I don't fit/like/recommend sorcerer as you pay for a name not a good product so I wouldn't know if a 40cdi/gti/sxi has a pump.

Ct-constant temp -what ever the boiler kicks out
VT-variable temp-decided by the controls

If keeping the ufh pump/manifold you wouldn't fit a mixing valve as thats what the pump/manifold/blending set does.

 

[dcawkwell]

Over complicating the problem me things. This is nothing special.

You have 30kw demand therefore any bog standard 35kw system boiler
is going to do the job. You will need extra expansion vessels in addition to the one in the boiler. Forget headers etc.

The most important thing that hasn't been mentioned is water supply.
Unless you have the flow for it forget running multiple showers etc.

You will certainly need a cold water accumulator in addition
to the unvented hot tank. I would be tempted to have two smaller
hot tanks rather than the brass pump if you have the room for it.

 

[Biggles..]

30kw demand....35kw cylinder coil?

 

[j1mmy]

I know... total loss calculator said only 2kw allocated for tank.

I think the theory is that tank won't need 35kW at the same time as house needing 30Kw ?

Else i would need a 65kw boiler and that just sounds like way over the top...

I guess if everything was cold from scratch there would be a high heat demand but average day would mean some latent heat in the system ??

 

[Biggles..]

Allow for the controls to ensure hot water priority,that way full blast to cylinder ensuring a compliant reheat from cold in 30mins.
My point over hot water usage would affect how you size the boiler,if you use all bathrooms and keep draining the tank 4-5 times a day then you'll need to allow heating loa at Te same time as water load.


I youve got the money/space and want very good efficient zones with good controls then a LLH with various circuits would be the dream.

 

[j1mmy]

dcawkwell I hear you on the flow pressure.

I will definitely need to triple check this. Seems it fluctuates depending on time of day / time of year.

I was kind of banking on the fact that I have approx 28m x 32mm pipe running from meter which should hold some water ?

if not, I have seen a home booster pump by Grundfos not sure if you guys have any thoughts on this system.

Also, I would be installing after softener so I guess would incur the pump coming on any time someone flushed a loo.. no way to avoid this as pipes have already been run all round house for wc supplies on same run as bath and shower supply.

 

[Biggles..]

If you mean the 200litre homebooster they're bang on as a break tank/pump set for domestic set ups.

 

[dcawkwell]

dcawkwell I hear you on the flow pressure.

I will definitely need to triple check this. Seems it fluctuates depending on time of day / time of year.

I was kind of banking on the fact that I have approx 28m x 32mm pipe running from meter which should hold some water ?

if not, I have seen a home booster pump by Grundfos not sure if you guys have any thoughts on this system.

Also, I would be installing after softener so I guess would incur the pump coming on any time someone flushed a loo.. no way to avoid this as pipes have already been run all round house for wc supplies on same run as bath and shower supply.

You need to measure the pressure you are getting and the flow.
You'll need approx 3 bar static and a good pressure when
flowing.
3 showers running at the same time is going to be using 30 litres a minute
and will consume a 300 litre unvented cylinder in 10 minutes.
So you'll need a minimum flow of 30 litres as well.
Bet you haven't got either of those in London.
I hope the plumbers have measured the flows and pressures.
If not I suggest you chuck whatever they have quoted straight in the bin.

 

[monoxide62]

LLH is a must due to each zone circuit requiring different flow/velocity rates.

As said , shunt/primary pump should be sized according to total system flow rate with head loss designed for boiler , primary pipework & header losses.

 

[DeltaT2]

Vaillant Eco tec plus 46 or 65 with Vaillant low loss. Shunt pump between boiler and LLH.(kw depend on cyl size and frequency of water usage)
Fit mixing valves to any heating circuit,ct for hot water.
Probably ditch the smaller pumps for a single circulator ( not sure why you've got 2 x 15/60's as that'd over kill).
Probably ditch the ufh pump as well if supplying as VT.

I'd use vaillants own controls for this.

Bit like this.

View media item 18024

I tend to agree with icgs a LLH is the way to go. Certainly the incoming mains water flow rate & pressure is a big concern, as you have a high Hot Water demand and with that in mind, a dedicated boiler or water heater for the Hot Water may be better? Certainly for cheaper running costs you want the boiler/boilers running at a 20 Delta T, so along with the incoming mains water, that should be a main concern - whatever system you install.

 

[Andygasman2010]

Over complicating the problem me things. This is nothing special.

You have 30kw demand therefore any bog standard 35kw system boiler
is going to do the job. You will need extra expansion vessels in addition to the one in the boiler. Forget headers etc.

I'd say this is the way to go. I agree that a LLH is the best way to go but it all depends how much money you want to spend. With a pump for each circuit, as well as a LLH etc... it can get expensive and over complicated.

I've just been involved in quoting for a very similar installation and when I added up all the boiler, controls, pumps, LLH, not to mention all the copper... it got very expensive and it looked like i'd never get the job!

Ended up quoting for a 30KW system boiler and extra expansion vessel.

Just do as dcawkwell said and make sure it's HW priority.

 

[dcawkwell]

I will probably be heckled for this but I suggest
3 ravenheat 42kw combi boilers one for each floor.
They are cheap currently 549 ex vat and give a flow rate
of 17 litres a minute of hot water.

You can add the energy catcher to the top of the unit to save an extra
7% on the hot water costs.

That will give you a maximum 51 litres of hot water a minute and a max heating ability of 105kW.

Simple easy solution and all it needs is a small cupboard on each floor for each boiler.

You'll need a big gas meter.