Ask a plumber/heating ‘engineer’ anything

[OutInTheShed]

Trustmeimadoctor said:

RustyMX5 said:

This one might be a head scratcher but I'll give it a punt.

4 bedroom 2 storey house on multiple levels (rear rooms are higher than the front rooms).

1 x shower room with toilet
1 x shower room
1 x bathroom
2 x toilet rooms

Because there isn't enough space in the loft for tanks there's a plant / utility room at floor 1 1/4 (the level at the rear of the ground level). The utility room contains a freezer, washing machine, 245 litre unvented hot water tank, a boiler, a water softener, 227 litre cold water tank and a Grundfos Scala II pump which pushes the cold water around the house.

My main issues are as follows:

The Grundfos pump, although it does a great job is bloody noisy.
The 227 litre cold tank is absolutely massive and I'd rather something smaller so I can use the sockets behind it for a tumble dryer or something else.

When I specced it with the plumber I went with no loss of pressure across any of the showers if they are running at the same time. The reality is that I probably went too high on the spec and the plumber delivered a solution which would deliver against that.

So what options are available to either do away with the tank / pump or just the tank?

do you mean pressure or flow rate, id assume flow rate.

how much do you want in lpm from each shower

The answer might depend on what the mains will deliver in terms of litres per minute into various pressures.
The trouble is, you can't expect a guaranteed supply pressure 100% of the time.
With decent thermostatic shower mixers, you should be able to accept a bit of pressure variation, it should not be like electric showers where the temperature is directly coupled to flow rate or fiddly mixers wich scald you if someone flushes a loo.

The rest of it depends what you want in terms of flow rate.
How badly do you want a powerful shower?
Personally we can run two showers which we find adequate without a pump.
It did involve choosing a suitable mixer and sprayhead and avoiding restrictive adaptors.

[Trustmeimadoctor]

Oh I agree but we need to establish what they actually want first
Even if the mains can't supply it you could use a buffer if you really need 45lpm for some reason

[Actual]

Trustmeimadoctor said:

people never listen when i say you dont need huge l/min for a shower

and you cetainly dont need it for a tap on a sink so get a 3lpm flow reducer in them

my shower is 5.4l/min is absolutely fine one issue is you cant just restrict any shower down and it be fine if its too big or the holes too big you do notice it but a well designed low flow head isnt hugely noticeable

fk that.

Moved to this house and the bathroom taps had a flow rate of 3.5L/min. I measured.

It took about 5 minutes for the hot to run hot let alone fill the basin.

Installed a mixer tap and specially chose one from Screwfix which was NOT labelled "Saving water at home" and now I get a glorious 17L/min.

[cayman-black]

Guys my stop cock has stopped shutting the water off and was wondering the best way to replace this can i change it from the front as its coming out of the cupboard backing,Thanks

[Regbuser]

There should be a water company stop valve in the outside pavement, like this



Firstly though, you'll have to improve access to your stop cock, which'll require removal of the cupboard back.

This will then let you see what will be required for repair of replacement of the valve.

I'd advise getting a plumber in to repair or replace, unless you are confident with mains water work.

[Sslink]

Our Honeywell ST9420C Sundial RF programmer died last week. We still have power to the Worcester Bosch Greenstar 30i boiler and I'm able to manually adjust the valve/microswitch to the HW circuit so we can have hot water without using the immersion.
Our local engineers (who were round for a non-related reason) told us the programmer is kaput and a like for like replacement will be close to £300.

For a programmer with limited functionality and no smart or even internet connected features, £300 feels a bit strong. They have recommended EPH 2 Zone RF programmer which can be internet connected with additional kit if required.

My question really is, what are my non-biased options? We have a Vented System. I would really like Priority Domestic HW which EPH appear to have a solution for but I understood that you needed flow temp control on the boiler which at present we don't have without the "optional diverter valve" being fitted to the boiler.

Thanks

[eltawater]

Assuming you need the wireless version, you can pick up the specific model of programmer as part of the two pack brand new from screwfix:

https://www.screwfix.com/p/honeywell-home-sundial-...

or you can find the controller ST9420C on ebay for between £50-£100. Just isolate the power, unscrew from beneath, lift off the old unit and fit the replacement.

[Sslink]

eltawater said:

Assuming you need the wireless version, you can pick up the specific model of programmer as part of the two pack brand new from screwfix:

https://www.screwfix.com/p/honeywell-home-sundial-...

or you can find the controller ST9420C on ebay for between £50-£100. Just isolate the power, unscrew from beneath, lift off the old unit and fit the replacement.

We've been told we need the 3-pack as we need a HW cylinder stat. No clue whether you can re-pair devices?

[bmwmike]

For a house heat loss calc of 16.9kw, am I correct in saying the boiler size should be heat loss + 3KW for DHW, so 16.9+3=19.9kw ?

Presumably so and in which case, an 18kw is no good, so i'd need the next size up, which is 24kw generally..

Thanks

[eltawater]

Sslink said:

eltawater said:

Assuming you need the wireless version, you can pick up the specific model of programmer as part of the two pack brand new from screwfix:

https://www.screwfix.com/p/honeywell-home-sundial-...

or you can find the controller ST9420C on ebay for between £50-£100. Just isolate the power, unscrew from beneath, lift off the old unit and fit the replacement.

We've been told we need the 3-pack as we need a HW cylinder stat. No clue whether you can re-pair devices?

Yes there's a binding menu on the controller. I have the 3 pack as well.

Start on page 18.

https://media.plumbarena.co.uk/uploads/files/2015/...

[Trustmeimadoctor]

bmwmike said:

For a house heat loss calc of 16.9kw, am I correct in saying the boiler size should be heat loss + 3KW for DHW, so 16.9+3=19.9kw ?

Presumably so and in which case, an 18kw is no good, so i'd need the next size up, which is 24kw generally..

Thanks

if i had heat loss of 17kw id be moving!

assume your wanting a combi as your have lumped DHW in with CH?

if so you need to look at the DHW flow rate but generally the higher the kw the more hot water it can supply but some are better than others


if its a system boiler then just 17kw would be enough as it doesnt do CH and DHW at the same time really

[bmwmike]

Trustmeimadoctor said:

bmwmike said:

For a house heat loss calc of 16.9kw, am I correct in saying the boiler size should be heat loss + 3KW for DHW, so 16.9+3=19.9kw ?

Presumably so and in which case, an 18kw is no good, so i'd need the next size up, which is 24kw generally..

Thanks

if i had heat loss of 17kw id be moving!

assume your wanting a combi as your have lumped DHW in with CH?

if so you need to look at the DHW flow rate but generally the higher the kw the more hot water it can supply but some are better than others


if its a system boiler then just 17kw would be enough as it doesnt do CH and DHW at the same time really

Thanks, that makes sense.

Am really looking at unvented + system boiler. I am not sure I want a combi. Space is tight though, as the place I have in mind to install everything is very specific.

Re heat loss I just did a quick online one, it was for sizing radiators i think. Maybe thats the wrong way to do it? Just put in the cubic size of each room, type of wall/floor/ceiling etc, and then it gave me BTU and watts for that room. I did that for every room, and got to 16.9kw.

[Trustmeimadoctor]

if you want to do it in more detail use this
https://heat-engineer.com

what temp was the heat loss calculated at? -3 is a safe one for most of england further north you go the lower the figure will be also need to take into account your elevation and if house is exposed etc as it can really alter what you really need

[B'stard Child]

Trustmeimadoctor said:

if you want to do it in more detail use this
https://heat-engineer.com

what temp was the heat loss calculated at? -3 is a safe one for most of england further north you go the lower the figure will be also need to take into account your elevation and if house is exposed etc as it can really alter what you really need

Agree with TMIAD - the heat engineer software is pretty good to use if you know the fabric of the building and can use a tape measure - it’s gonna get you pretty damn close.

4 bed detached with a 24kW boiler (previous heating engineer calculated I’d need 18 kW but that was before an extension - actual heat loss 4.3 kW at -2

PS 17kWh heat loss I’d be moving too

[bmwmike]

Ok sounds like I may be way off with the heat loss calc then!! I used this tool, room by room:

https://www.bestheating.com/btu-calculator

It's a detached bungalow, extended in 1990s with fairly decent for the time insulation, approx 210sqm, so I doubt it's as bad as the calc makes out.. hopefully !!

Ps if I can't have a unvented cylinder and system boiler, would I hate a combi? I am really stuck for space as we've canned the idea of an extension due to quotes of 70k for a new room, effectively, which was going to make way for a utility. Decided not to play the game. But as I need a new boiler and cylinder it has to go in a space approx 1m wide by 70cm deep by 2.7m height. Or a combi.

[Trustmeimadoctor]

Combi isn't an issue if you buy the right one and have enough mains flow rate. But the right combi may be more than a system boiler and tank

What are your needs and desires

[bmwmike]

Trustmeimadoctor said:

Combi isn't an issue if you buy the right one and have enough mains flow rate. But the right combi may be more than a system boiler and tank

What are your needs and desires

3 showers (may keep one electric), a bath, 14 rads.

My needs - ability to use hot water and not have to think about it or be aware that someone is showering etc. ideally use 2 showers briefly at a time. Have a shower and not have a hot tap or two make it go cold?

Flow is 18lpm, pressure good (4 bar static, I think, maybe wildly off remembering).

Any suggestions or am I dreaming of the impossible

Edited by bmwmike on Tuesday 4th June 22:36

[bmwmike]

Trustmeimadoctor said:

Combi isn't an issue if you buy the right one and have enough mains flow rate. But the right combi may be more than a system boiler and tank

What are your needs and desires

Whats an example of "the right one" in terms of a combi please and can it run multiple showers/hot taps?

[Trustmeimadoctor]

https://viessmanndirect.co.uk/Catalogue/Residentia...

https://viessmanndirect.co.uk/Catalogue/Residentia...

they can both supply multiple the 222 can obviously supply way more than the 111

other storage combi's are also available but im a sucker for a viessmann

or you could get a combi and a separate tank if you wanted

[bmwmike]

Trustmeimadoctor said:

https://viessmanndirect.co.uk/Catalogue/Residentia...

https://viessmanndirect.co.uk/Catalogue/Residentia...

they can both supply multiple the 222 can obviously supply way more than the 111

other storage combi's are also available but im a sucker for a viessmann

or you could get a combi and a separate tank if you wanted

Ahhh ok am back to storage combi's - I was told they are the worst compromise of both worlds - combi and system+storage. I will take a look again i guess. I though you were referring to vanilla combi's.