Has anyone had any experience with Chelmer Heating?

[Jenni]

On the question of Chelmer Heating, they're only an hour from us, we visited them (2019), got quotes etc, was very impressed. Then some very odd stuff happened, some fundamental things said previously were contradicted then denied, then the guy got very defensive and quite rude, even appearing to have a 'drunken' rant.

Needless to say we lost trust and went elsewhere. 

[Post and beam]

I have had a quote from them today, initiated out of this thread. ASHP(SAMSUNG 12KW) 350L cylinder, UFH hardware and a few design bits and sundry plumbing parts. Dont understand the plumbing bits but i'm sure they are necessary.

£12300 + VAT supply only. So, very nearly £15k

[JohnMo]

5 hours ago, sharpener said:

charge a buffer tank to Tmax (?70) in order to feed the bedroom rads

Just put an electric element in the bathroom rads.  Why heat a huge volume of water, pump it around when you can heat the bathroom rads which contain a few litres of water. They work all year round if you want, with the heating off.

[JohnMo]

6 minutes ago, Post and beam said:

£12300 + VAT supply only. So, very nearly £15k

That's a bonkers price for supply only

 

How big is your house going to be to need that size of heat pump. I could run 600m2 with that size of heat pump, and have room to spare.

[Post and beam]

4 minutes ago, JohnMo said:

How big is your house going to be to need that size of heat pump

Its 201m2 when built. I dont believe it will need that size of pump.

 

4 minutes ago, JohnMo said:

That's a bonkers price for supply only

Yes it is.

I am beginning to despair of this whole racket.

[sharpener]

22 minutes ago, JohnMo said:

Just put an electric element in the bathroom rads.  Why heat a huge volume of water, pump it around when you can heat the bathroom rads which contain a few litres of water. They work all year round if you want, with the heating off.

 

bedroom rads. 6 of them.

[sharpener]

32 minutes ago, Post and beam said:

Its 201m2 when built. I dont believe it will need that size of pump.

 

Yes it is.

I am beginning to despair of this whole racket.

 

What is the construction? Thanks to Heat Geek a useful cheat sheet below.

 

For our barn conversion I took a figure from this of 75 W/m^2 to represent stone walls with double glazing and thick loft insulation. Result of 15kW agrees closely with the more detailed rads total from cityplumbing web site of 14.86kW, though that did not include the kitchen area as it has the Aga.

 

 

 

Edited April 5, 2023 by sharpener

[JohnMo]

9 hours ago, sharpener said:

bedroom rads. 6 of them.

The discussion was bathroom rads not bedroom.

[JohnMo]

You really need to calculate the heat loss, rules of thumb and heat pumps is not good enough. Rules of thumb and heat pumps is a recipe for high running costs.

 

I used the city plumbing app and how house needed around 14kW, in fact the correct size is just over 3kW.

Edited April 6, 2023 by JohnMo
Missed details

[sharpener]

12 hours ago, JohnMo said:

The discussion was bathroom rads not bedroom.

 

I never said anything about the bathroom rads - because there aren't any.

12 hours ago, JohnMo said:

You really need to calculate the heat loss, rules of thumb and heat pumps is not good enough. Rules of thumb and heat pumps is a recipe for high running costs.

 

I used the city plumbing app and how house needed around 14kW, in fact the correct size is just over 3kW.

 

It was only meant as a sanity check. But do you have any explanation for how these figures above come to be so radically different?

 

The city plumbing calculator looks more or less identical with the one on several other plumbers' merchants' web site (cosmetics apart) but I do not know where it originally came from. It seems to take account of quite a number of underlying variables but I have no idea of its accuracy.

 

I do know that the result is not very sensitive to the exact window sizes for example, however I don't know if 50cm thick traditional stone walls are very different from 9 in brick with no cavity, or how much of the total heat loss this represents. Certainly the thermal mass will be a lot greater, but in the steady state this will not matter and I would expect the thermal conductivity to be less. The whole lot might anyway be swamped by errors in the ventilation rate assumptions for all I know.

 

As a relative latecomer to all this I would appreciate a link to a better online calculator if there is one e.g. the mythical Jeremy H, for rough sizing only so I am not looking wholly in the wrong ballpark for HPs.

[JohnMo]

The problem with city plumbing calculation and many other is it's based on general rules of thumb, no input for air changes, only does generic double glazing, flat roof insulated, no idea what u value is used, same for the wall and floor.

 

Just re did one room the kitchen, and it was equal to my entire house heat loss. 

 

It's just a selling tool for radiators. 

 

A few years ago I used the same tool for sizing radiators for our last house, an 1830s house, it just as rubbish for that house, said my living room needed 4 huge radiators, doing the calcs long hand it only needed one large radiator. No issues heating the room.

 

This spreadsheet works pretty well, does the house as a single entity not room by room. It doesn't take account of people in the building and other heat sources, so does over state the heating in warm or mild months, but for the design case condition it pretty good.

 

https://forum.buildhub.org.uk/topic/439-fabric-and-ventilation-heat-loss-calculator/

[JohnMo]

1 hour ago, sharpener said:

never said anything about the bathroom rads

Sorry just re read, I must have been on a tangent - you did say bedrooms.

[sharpener]

What do ppl think of the Heat Engineer s/w? £10 for a one-off survey seems almost too good to miss and the HelpGuide a lot of useful information. But if there are negative views here I might not spend any more time on it.

[SteamyTea]

Not a lot

 

[JohnMo]

Having a read of the helpguide, it mentions degree-days being above 15.5 degrees heating isn't required, below 15.5 it is.  This is a variable and really depends on the insulation levels of the property, well insulated could set that at about 10 to 11 degrees. So not perfect.  I would just use the spreadsheet I linked to. It costs nothing except 30mins of your time.

[SteamyTea]

3 hours ago, JohnMo said:

Having a read of the helpguide, it mentions degree-days being above 15.5 degrees heating isn't required, below 15.5 it is.  This is a variable and really depends on the insulation levels of the property, well insulated could set that at about 10 to 11 degrees. So not perfect.  I would just use the spreadsheet I linked to. It costs nothing except 30mins of your time.

My 'heating on' daily mean temperature is now 9°C.  Used to be 10°C.

It is why a 1°C drop in house temperature can make a large saving on energy costs.  We tend to have more days where the temperature is between 6°C and 10°C than we do -1°C and 3°C.

I also think that HDDs are one of the few metrics that benefit smaller houses, though not actually analysis it too closely yet.  My cooker, which has been on less than 30 minutes, has increased my house temperature by over 1°C.