Alternatives To An ASHP

[Matt60]

1 hour ago, joe90 said:

I much prefer solid render/plaster 

 

Do you just mean plaster straight on to the block work?

[TonyT]

Isn’t dot and dab ok as long as the dots and dabs are a continuous ribbon around the perimeter of the board, supplemented with intermediate dabs? 

[pdf27]

40 minutes ago, Matt60 said:

My last house was a 1985 place built as a pair by a local builder, it was heated by an oil boiler. I can't help but wonder with the efficiencies of the new place if an oil boiler might make sense? I'm not all that keen on putting such an old fashioned solution in but it would be cheap to install and produce enough heat. Thoughts? 

Minimum size you can get an oil boiler is about 12kW - if you're doing a reasonably efficient build then that's going to be massively oversized and give you all sorts of problems.

[Matt60]

1 minute ago, pdf27 said:

Minimum size you can get an oil boiler is about 12kW - if you're doing a reasonably efficient build then that's going to be massively oversized and give you all sorts of problems.

 

Excuse my ignorance, genuinely, but how would it cause problems?

[SteamyTea]

1 minute ago, pdf27 said:

Minimum size you can get an oil boiler is about 12kW - if you're doing a reasonably efficient build then that's going to be massively oversized and give you all sorts of problems.

Am I right in thinking that while oil boilers can condense, they do not modulate their power?

[pdf27]

1 minute ago, Matt60 said:

 

Excuse my ignorance, genuinely, but how would it cause problems?

 

Just now, SteamyTea said:

Am I right in thinking that while oil boilers can condense, they do not modulate their power?

Correct - there are a handful of "modulating" boilers out there which as I understand it just have two burners which they can use individually or in parallel, but they're rare. Essentially it means you'll be dumping 12kW into a house which needs maybe 1kW on an average day, which will make controlling the temperature for comfort hard. Ideally the boiler would be matched to the design cold day demand, in which case on an average day it would be on maybe a third of the time in which case the temperature stability will be a lot better. Cycling is an issue for reliability, but my main concern would be comfort.

[Matt60]

5 minutes ago, pdf27 said:

 

Correct - there are a handful of "modulating" boilers out there which as I understand it just have two burners which they can use individually or in parallel, but they're rare. Essentially it means you'll be dumping 12kW into a house which needs maybe 1kW on an average day, which will make controlling the temperature for comfort hard. Ideally the boiler would be matched to the design cold day demand, in which case on an average day it would be on maybe a third of the time in which case the temperature stability will be a lot better. Cycling is an issue for reliability, but my main concern would be comfort.

 

I see, that makes sense - thankyou.

[joe90]

2 hours ago, Matt60 said:

 

Do you just mean plaster straight on to the block work?

With my build i specified cement render first coat and plaster second coat

 

1 hour ago, TonyT said:

Isn’t dot and dab ok as long as the dots and dabs are a continuous ribbon around the perimeter of the board, supplemented with intermediate dabs? 

 

so I am told but I still don’t like “hollow” walls, solid all the way fir me, fix/hang anything anywhere!!! (Plus I am an advocate of “thermal mass ?)

[TerryE]

2 hours ago, TonyT said:

Isn’t dot and dab ok as long as the dots and dabs are a continuous ribbon around the perimeter of the board, supplemented with intermediate dabs? 

 

The issue here is gaps in the mortar.  Let's say behind one board you have a gap near the bottom and another at the top, so you get cold air coming in at the bottom, being nicely heated to say 20°C by that nice board radiator and cycling back out at the top crack.  The net result is that the void behind the board is cycling heat into the void between the brick and blockwork courses.  I've seen horror story FIR walk-arounds where external walls are 10° colder than they should be because of this.  You can't tell it is happening until the house is built and fully heated and by that stage the cost of remediation is prohibitive.    I've also seen cases where it is clear from the FIR camera that whole areas of cavity insulation have been omitted.

 

If this happens, by this stage what realistic remediation or recompense do you have from your builder?  As @joe90 says, one option is to parge the wall with a cement slurry to seal the blockwork properly.  Another is to go over it with a "fine tooth comb" before it is plaster boarded out, but this level of inspection is skilled and tedious.

 

 

[TerryE]

Re the issue of cycling boilers, let's say you need 2 kW and you have a 12 kW boiler, this the boiler will be on:off on a roughly 1:5 cycle.  Boilers need to be on for a decent block at a go, say 20 mins, this means that you will need to be off for 1h40 between each on and you will need a buffer tank capable of storing ~ 5kWh heat.  

[Matt60]

Thanks for all the replies here, there is some really useful stuff, I will definitely use a cement slurry or render and plaster coat rather than just straight dot and dab.

 

10 hours ago, joe90 said:

With my build i specified cement render first coat and plaster second coat

 

 

Would a plasterer be able to do the render coat, presumably most good one would?

[PeterW]

19 minutes ago, Matt60 said:

Thanks for all the replies here, there is some really useful stuff, I will definitely use a cement slurry or render and plaster coat rather than just straight dot and dab.

 

 

Would a plasterer be able to do the render coat, presumably most good one would?

 You can do it yourself. 4-1 sand cement and mix to a slurry. Cheap sweeping brush and a big plastic box and just dip, sweep, repeat ..!

[Matt60]

40 minutes ago, PeterW said:

 You can do it yourself. 4-1 sand cement and mix to a slurry. Cheap sweeping brush and a big plastic box and just dip, sweep, repeat ..!

 

Yeah I got that and would do if I went with the slurry coat. What I need to know is with a render coat, would most good plasterers be able to do that? The latter would be my preference for the reasons @joe90 said.

 

Thanks.

[PeterW]

7 minutes ago, Matt60 said:

 

Yeah I got that and would do if I went with the slurry coat. What I need to know is with a render coat, would most good plasterers be able to do that? The latter would be my preference for the reasons @joe90 said.

 

Thanks.

You mean someone to do it with hard wall ..? So a bonding coat then browning / top coat plaster (it’s plaster inside, render outside) which is the traditional way of doing it. 
 

A good plasterer should be able to do that no problem, finding a good plasterer though will be your challenge as I’ve seen some jobs that are as rough as toast when it’s not just a board and skim job. 

[joe90]

2 hours ago, Matt60 said:

 

Yeah I got that and would do if I went with the slurry coat. What I need to know is with a render coat, would most good plasterers be able to do that? The latter would be my preference for the reasons @joe90 said.

 

Thanks.

Yes, mine was good, cement render instead of parge coat then  Thin plaster top coat. Cement render is cheaper than hard wall for first coat! But I did parge coat between joists etc so no leakage between floors!

Edited February 28, 2021 by joe90

[Dave Jones]

without reading all 3 pages, gas combi is way to go. Will not be beaten on price and running cost by any other system.

[SteamyTea]

3 hours ago, Dave Jones said:

without reading all 3 pages, gas combi is way to go. Will not be beaten on price and running cost by any other system.

Do they have lower CO₂ emissions?

Should they have an annual service?

If they are in a rental, do they need a safety certificate?

Can they be easily installed by a 'normal' home owner that can do DIY?

Do they need a dedicated supply and meter if one is not already installed?

How do you proportion the meter rental?

And the big one, if no mains gas is available, are they still suitable?

 

You really do not like heat pumps do you.

[Dave Jones]

2 minutes ago, SteamyTea said:

Do they have lower CO₂ emissions?

Should they have an annual service?

If they are in a rental, do they need a safety certificate?

Can they be easily installed by a 'normal' home owner that can do DIY?

Do they need a dedicated supply and meter if one is not already installed?

How do you proportion the meter rental?

And the big one, if no mains gas is available, are they still suitable?

 

You really do not like heat pumps do you.

 

its not rocket science.

 

heat pump = 10k and 5 min showers then you freeze. dont work when its cold etc

combi = £750 limitless cheap hot water.

 

And no i dont like them they are expensive and give a substandard service.

 

 

 

 

[joe90]

6 minutes ago, Dave Jones said:

heat pump = 10k and 5 min showers then you freeze. dont work when its cold etc

Sorry Dave but you have no idea at all about heat pumps do you. Yes they are not a direct replacement for a gas boiler but many people (me included) have a very good working heat pump, the only ones that don’t work properly are those that are not designed properly (p.s. I designed my own installation and I am not a rocket scientist?‍♂️).

[SteamyTea]

10 minutes ago, Dave Jones said:

its not rocket science.

That is the only true statement in your reply.

It is thermodynamics.

11 minutes ago, Dave Jones said:

heat pump = 10k and 5 min showers then you freeze. dont work when its cold etc

Show me the data that they cost 10k and only supply 5 minutes of hot water?  Or stop talking nonsense.

 

[Dave Jones]

2 minutes ago, joe90 said:

Sorry Dave but you have no idea at all about heat pumps do you. Yes they are not a direct replacement for a gas boiler but many people (me included) have a very good working heat pump, the only ones that don’t work properly are those that are not designed properly (p.s. I designed my own installation and I am not a rocket scientist?‍♂️).

 

you are the exception that proves the rule Joe!

 

They will only ever be a niche product, how is a council house family of 5 meant to get 5 baths and hot water and heating out of one in 24 hours for less than £60 a month in utility bills ?

 

Worcester Bosche have the right idea.

[Dave Jones]

2 minutes ago, SteamyTea said:

That is the only true statement in your reply.

It is thermodynamics.

Show me the data that they cost 10k and only supply 5 minutes of hot water?  Or stop talking nonsense.

 

 

your saying they provide cheap  limitless hot water ? Thought not.

[SteamyTea]

1 minute ago, Dave Jones said:

your saying they provide cheap  limitless hot water ? Thought not.

I am saying that they can supply as much domestic hot water as you want.  You name the quantity, I hall find a solution for you.

Edited February 28, 2021 by SteamyTea

[Dave Jones]

1 minute ago, SteamyTea said:

I am saying that they can supply as much domestic hot water as you want.  You name the quantity, I hall find a solution for you.

 

i agree at a cost. 

 

Design me a solution that does it cheaper than a combi.

[SteamyTea]

1 minute ago, Dave Jones said:

i agree at a cost. 

So half way there then.

 

I was answering you uneducated assertion that a heat pump can only supply 5 minutes of hot water.

 

Go and read all 3 pages of the thread and see what it is about before spouting your usual nonsense about heat pumps.