We’re in the process of renovating our basement, which includes changing the radiators and I’m looking for advice regarding my piping situation.
There are radiators in the rooms I want to heat in the basement, but they are too small and will be replaced by type 33 with fans underneath that deliver sufficient power at my current design flow temperatures (34°C@ -10°C outside).
The flow/return pipes were put in the concrete base plate without any insulation by the previous owner, hence there is some heat loss to the ground as the heat is being conducted away. The question is how much and whether it makes sense to also lay new insulated pipes along the ceiling instead. What I’m looking for is some empirical calculation that will tell me the unusable heat loss in this situation.
Say I have a concrete base slab of some thickness that is on all sides (except the top) surrounded by the ground. A pipe of certain diameter is embedded at a certain depth. Some of the heat will be conducted into the ground (P_Ground), some of it will heat the basement rooms (P_Room) where the pipe passes through.
What I’m looking for are equations giving me P_Ground and P_Room as functions of concrete characteristics, flow temperature, room temperature and surrounding ground temperature. I just want to be able to estimate whether I would ever recover the investment of laying new pipework by the energy savings.
i have a set of sensors inside the plant room and comparing these to the HP leaving temp there is around 1-1.5 degree difference but they are not the same type of sensors
Yeah I guess I could just measure it, that hadn’t even crossed my mind. I will just build some sensors. Still an empirical equation would be good to compare.
If it is, wouldn’t it be better to use these temperature sensors to feed you data?
That is what a heat meter does, installed in the house, not measuring at the heat pump outside.
Obviously, some heat is lost outside, one reason why data straight from the heat pump is not necessarily representative of what is really going into the house.
Yes; if you can be bothered and the concrete is directly on the ground.
No; if the concrete is itself above an insulation layer and this becomes underfloor heating.
If the concrete is directly on the ground then a wooden floor sat on top of it might add materially to thermal comfort by avoiding feet on cold concrete
The wdc is set in the MMI and is not related to the data sent to emoncms
Same as me, my lwt is set in the MMI/app but my data sent to emoncms comes from the heat meter. you can set your wdc on the MMI and then report heat actually delivered to your home from the sensors in your plant room?
They are not connected, and neither should they be. The heat delivered to a home needs to be measured where the water enters and leaves that home, otherwise it is including any heat lost to the outside world.
I guess this means that your reported heat produced is at the heat pump and not in your actual home?
You are correct i am using data from the HP measuring the heat loss of the whole system including to the outside, i did realise this when i set up my system and purposely used data from the HP , its unlikely everyone who is using heat pump data is doing the same, ie data from the heat pump with no internal sensors other than the room temp
as mentioned earlier i loose between 1-1.5 degrees C from the heat pump to the plant room on the flow the return is hardly measurable 0.1 at most
i also realise this probably makes my COP SCOPS look worse than others are measuring but in my eyes we need to look at the system as a whole not just the heat loss in the house
I was just surprised, that if you have sensors inside the plant room, that you don’t use them as that would give a more accurate report of actual performance that would be more comparable to a MID system.
That has to be more beneficial to you and everybody else that looks?
I dare say the heat produced would be less and the COP would be lower, but it would be more accurate and more comparable to `properly’ monitored systems.
But, it is up to you, of course.
Makes no difference to me as I only ever take MID monitored systems `seriously’
That means your heat production and COP/SCOP is massively over reported.
Imagine if you knocked 1.0 to 1.5c off your flow temperature and only 0.1c off the return.
Your heat produced would drop to about two thirds of what you show and the COP would be proportionately less.
If your internal sensors are correct, then about a third of the heat you produce is heating up Northwich!
You are not under reporting your COP/SCOP making it look worse than others, you are doing the opposite, making it look better than it really is assuming the sensors in your plant room are accurate.
For no other reason, I’d have a look at the insulation on your flow pipe work to see if you can improve it.
If the sensors in your plant room are accurate, then your COP is much worse than you think and the heat getting to your home is much less than you think it is.
It could be improved?
MID systems look at heat to the home as the heat meters are usually within the heated part of the building. you should be looking to compare with those as that will tell you how well your system is really performing, they are the only verifiably accurate systems.
Is everyone else who is using heat pump (integration) data , have separate sensors internally ?
my pipe work outside is approx 4 metres then there is a other 5 metres of internal pipework (all 28mm) to the plant room before the extra sensors near the water tank and the three port valve
i only added the internal sensors to see what the external heat pump loss loss was to the water tank
We are talking about your home and the performance of your heat pump, forget anybody else.
1.0 to 1.5c difference in flow temperature is a lot at a DT of 5c, about 20% to 30%
If the flow temperature really drops that much between the heat pump and when it enters your home then I would be concerned.
Just as @Andre_K is about losing heat in buried pipes.
If your measurements are accurate, then you are losing a lot of heat to the outside world, it would bother me.
In terms of what is important to know, what would you be most interested in, how much heat a heat pump created (including what goes in the garden), or how much heat a heat pump can get in your house?
Nobody buys a heat pump to just get a good COP, otherwise we’d all get one and attach a radiator to it in the garden and all get a great COP. They are bought and installed to heat homes.
What we all want to know is how much heat gets into the home and how much electricity does it take to do it.
My Daikin heat pump is no more efficient than yours or anybody else’s, they are all the same.
my guess would be the internal temp sensors are not that accurate, as they are pt100 sensors taped to the pipe work i also move them around just to see what is happening in different parts of the system . ie @water tank flow and return and just central heating , ive even used them to measure incoming water to tank and water leaving the tank & temp difference across the volumiser
also ive just changed my dt target temp to 8 degrees (just playing with the system to what changes have what effects
i am not really interested in the cop and scops as such i am more interested in playing with the heat pump setting and see what improves efficiency and what does not, plus what i have would pick up any issues that might arise. i understand why installers might want to fit the full kit but i am more interested in what happens when i change things ,
and in reality i was more interested in getting the data in to home assistant originally but once i stumbled on heat pump monitor and saw i could intergrate the data in to here i was more than happy
No worries, I’ve hijacked my own share of threads . We’ll put in new pipes, they are quite cheap and we can do most of the work ourselves without having to pay for someone.
